Revert "Teach drag start behaviors to DragGestureRecognizer (#23424)" (#26209) This reverts commit 08538f91f0b7f3f448355e998bb536b06a1d1145.

diff --git a/examples/flutter_gallery/lib/demo/material/drawer_demo.dart b/examples/flutter_gallery/lib/demo/material/drawer_demo.dart
index a978199..3f08bde 100644
--- a/examples/flutter_gallery/lib/demo/material/drawer_demo.dart
+++ b/examples/flutter_gallery/lib/demo/material/drawer_demo.dart

@@ -3,7 +3,6 @@
 // found in the LICENSE file.
 
 import 'package:flutter/material.dart';
-import 'package:flutter/gestures.dart' show DragStartBehavior;
 
 import '../../gallery/demo.dart';
 
@@ -80,7 +79,6 @@
   @override
   Widget build(BuildContext context) {
     return Scaffold(
-      drawerDragStartBehavior: DragStartBehavior.down,
       key: _scaffoldKey,
       appBar: AppBar(
         leading: IconButton(
@@ -108,7 +106,6 @@
               ),
               otherAccountsPictures: <Widget>[
                 GestureDetector(
-                  dragStartBehavior: DragStartBehavior.down,
                   onTap: () {
                     _onOtherAccountsTap(context);
                   },
@@ -123,7 +120,6 @@
                   ),
                 ),
                 GestureDetector(
-                  dragStartBehavior: DragStartBehavior.down,
                   onTap: () {
                     _onOtherAccountsTap(context);
                   },
@@ -153,7 +149,6 @@
               removeTop: true,
               child: Expanded(
                 child: ListView(
-                  dragStartBehavior: DragStartBehavior.down,
                   padding: const EdgeInsets.only(top: 8.0),
                   children: <Widget>[
                     Stack(

diff --git a/examples/flutter_gallery/lib/demo/material/text_form_field_demo.dart b/examples/flutter_gallery/lib/demo/material/text_form_field_demo.dart
index 4deab75..ddbea4b 100644
--- a/examples/flutter_gallery/lib/demo/material/text_form_field_demo.dart
+++ b/examples/flutter_gallery/lib/demo/material/text_form_field_demo.dart

@@ -6,7 +6,6 @@
 
 import 'package:flutter/material.dart';
 import 'package:flutter/services.dart';
-import 'package:flutter/gestures.dart' show DragStartBehavior;
 
 import '../../gallery/demo.dart';
 
@@ -68,7 +67,6 @@
         labelText: widget.labelText,
         helperText: widget.helperText,
         suffixIcon: GestureDetector(
-          dragStartBehavior: DragStartBehavior.down,
           onTap: () {
             setState(() {
               _obscureText = !_obscureText;
@@ -169,7 +167,6 @@
   @override
   Widget build(BuildContext context) {
     return Scaffold(
-      drawerDragStartBehavior: DragStartBehavior.down,
       key: _scaffoldKey,
       appBar: AppBar(
         title: const Text('Text fields'),
@@ -183,7 +180,6 @@
           autovalidate: _autovalidate,
           onWillPop: _warnUserAboutInvalidData,
           child: SingleChildScrollView(
-            dragStartBehavior: DragStartBehavior.down,
             padding: const EdgeInsets.symmetric(horizontal: 16.0),
             child: Column(
               crossAxisAlignment: CrossAxisAlignment.stretch,

diff --git a/examples/stocks/lib/stock_home.dart b/examples/stocks/lib/stock_home.dart
index f13b51b..c77134e 100644
--- a/examples/stocks/lib/stock_home.dart
+++ b/examples/stocks/lib/stock_home.dart

@@ -5,7 +5,6 @@
 import 'package:flutter/material.dart';
 import 'package:flutter/rendering.dart' show debugDumpRenderTree, debugDumpLayerTree, debugDumpSemanticsTree, DebugSemanticsDumpOrder;
 import 'package:flutter/scheduler.dart' show timeDilation;
-import 'package:flutter/gestures.dart' show DragStartBehavior;
 import 'stock_data.dart';
 import 'stock_list.dart';
 import 'stock_strings.dart';
@@ -111,7 +110,6 @@
   Widget _buildDrawer(BuildContext context) {
     return Drawer(
       child: ListView(
-        dragStartBehavior: DragStartBehavior.down,
         children: <Widget>[
           const DrawerHeader(child: Center(child: Text('Stocks'))),
           const ListTile(
@@ -319,13 +317,11 @@
     return DefaultTabController(
       length: 2,
       child: Scaffold(
-        drawerDragStartBehavior: DragStartBehavior.down,
         key: _scaffoldKey,
         appBar: _isSearching ? buildSearchBar() : buildAppBar(),
         floatingActionButton: buildFloatingActionButton(),
         drawer: _buildDrawer(context),
         body: TabBarView(
-          dragStartBehavior: DragStartBehavior.down,
           children: <Widget>[
             _buildStockTab(context, StockHomeTab.market, widget.stocks.allSymbols),
             _buildStockTab(context, StockHomeTab.portfolio, portfolioSymbols),

diff --git a/packages/flutter/lib/src/cupertino/switch.dart b/packages/flutter/lib/src/cupertino/switch.dart
index f32b2d8..bbb1d7a 100644
--- a/packages/flutter/lib/src/cupertino/switch.dart
+++ b/packages/flutter/lib/src/cupertino/switch.dart

@@ -52,16 +52,12 @@
 ///  * <https://developer.apple.com/ios/human-interface-guidelines/controls/switches/>
 class CupertinoSwitch extends StatefulWidget {
   /// Creates an iOS-style switch.
-  ///
-  /// [dragStartBehavior] must not be null.
   const CupertinoSwitch({
     Key key,
     @required this.value,
     @required this.onChanged,
     this.activeColor,
-    this.dragStartBehavior = DragStartBehavior.start,
-  }) : assert(dragStartBehavior != null),
-       super(key: key);
+  }) : super(key: key);
 
   /// Whether this switch is on or off.
   final bool value;
@@ -96,26 +92,6 @@
   /// [CupertinoTheme] in accordance to native iOS behavior.
   final Color activeColor;
 
-  /// {@template flutter.cupertino.switch.dragStartBehavior}
-  /// Determines the way that drag start behavior is handled.
-  ///
-  /// If set to [DragStartBehavior.start], the drag behavior used to move the
-  /// switch from on to off will begin upon the detection of a drag gesture. If
-  /// set to [DragStartBehavior.down] it will begin when a down event is first
-  /// detected.
-  ///
-  /// In general, setting this to [DragStartBehavior.start] will make drag
-  /// animation smoother and setting it to [DragStartBehavior.down] will make
-  /// drag behavior feel slightly more reactive.
-  ///
-  /// By default, the drag start behavior is [DragStartBehavior.start].
-  ///
-  /// See also:
-  ///
-  ///  * [DragGestureRecognizer.dragStartBehavior], which gives an example for the different behaviors.
-  /// {@endtemplate}
-  final DragStartBehavior dragStartBehavior;
-
   @override
   _CupertinoSwitchState createState() => _CupertinoSwitchState();
 
@@ -135,7 +111,6 @@
       activeColor: widget.activeColor ?? CupertinoColors.activeGreen,
       onChanged: widget.onChanged,
       vsync: this,
-      dragStartBehavior: widget.dragStartBehavior,
     );
   }
 }
@@ -147,14 +122,12 @@
     this.activeColor,
     this.onChanged,
     this.vsync,
-    this.dragStartBehavior = DragStartBehavior.start,
   }) : super(key: key);
 
   final bool value;
   final Color activeColor;
   final ValueChanged<bool> onChanged;
   final TickerProvider vsync;
-  final DragStartBehavior dragStartBehavior;
 
   @override
   _RenderCupertinoSwitch createRenderObject(BuildContext context) {
@@ -164,7 +137,6 @@
       onChanged: onChanged,
       textDirection: Directionality.of(context),
       vsync: vsync,
-      dragStartBehavior: dragStartBehavior
     );
   }
 
@@ -175,8 +147,7 @@
       ..activeColor = activeColor
       ..onChanged = onChanged
       ..textDirection = Directionality.of(context)
-      ..vsync = vsync
-      ..dragStartBehavior = dragStartBehavior;
+      ..vsync = vsync;
   }
 }
 
@@ -200,7 +171,6 @@
     ValueChanged<bool> onChanged,
     @required TextDirection textDirection,
     @required TickerProvider vsync,
-    DragStartBehavior dragStartBehavior = DragStartBehavior.start,
   }) : assert(value != null),
        assert(activeColor != null),
        assert(vsync != null),
@@ -218,8 +188,7 @@
     _drag = HorizontalDragGestureRecognizer()
       ..onStart = _handleDragStart
       ..onUpdate = _handleDragUpdate
-      ..onEnd = _handleDragEnd
-      ..dragStartBehavior = dragStartBehavior;
+      ..onEnd = _handleDragEnd;
     _positionController = AnimationController(
       duration: _kToggleDuration,
       value: value ? 1.0 : 0.0,
@@ -307,14 +276,6 @@
     markNeedsPaint();
   }
 
-  DragStartBehavior get dragStartBehavior => _drag.dragStartBehavior;
-  set dragStartBehavior(DragStartBehavior value) {
-    assert(value != null);
-    if (_drag.dragStartBehavior == value)
-      return;
-    _drag.dragStartBehavior = value;
-  }
-
   bool get isInteractive => onChanged != null;
 
   TapGestureRecognizer _tap;

diff --git a/packages/flutter/lib/src/gestures/monodrag.dart b/packages/flutter/lib/src/gestures/monodrag.dart
index c823311..4c25e68 100644
--- a/packages/flutter/lib/src/gestures/monodrag.dart
+++ b/packages/flutter/lib/src/gestures/monodrag.dart

@@ -2,8 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-import 'package:flutter/foundation.dart';
-
 import 'arena.dart';
 import 'constants.dart';
 import 'drag_details.dart';
@@ -50,36 +48,7 @@
 ///  * [PanGestureRecognizer], for drags that are not locked to a single axis.
 abstract class DragGestureRecognizer extends OneSequenceGestureRecognizer {
   /// Initialize the object.
-  ///
-  /// [dragStartBehavior] must not be null.
-  DragGestureRecognizer({
-    Object debugOwner,
-    this.dragStartBehavior = DragStartBehavior.start,
-  }) : assert(dragStartBehavior != null),
-       super(debugOwner: debugOwner);
-
-  /// Configure the behavior of offsets sent to [onStart].
-  ///
-  /// If set to [DragStartBehavior.start], the [onStart] callback will be called at the time and
-  /// position when the gesture detector wins the arena. If [DragStartBehavior.down],
-  /// [onStart] will be called at the time and position when a down event was
-  /// first detected.
-  ///
-  /// For more information about the gesture arena:
-  /// https://flutter.io/docs/development/ui/advanced/gestures#gesture-disambiguation
-  ///
-  /// By default, the drag start behavior is [DragStartBehavior.start].
-  ///
-  /// ## Example:
-  ///
-  /// A finger presses down on the screen with offset (500.0, 500.0),
-  /// and then moves to position (510.0, 500.0) before winning the arena.
-  /// With [dragStartBehavior] set to [DragStartBehavior.down], the [onStart]
-  /// callback will be called at the time corresponding to the touch's position
-  /// at (500.0, 500.0). If it is instead set to [DragStartBehavior.start],
-  /// [onStart] will be called at the time corresponding to the touch's position
-  /// at (510.0, 500.0).
-  DragStartBehavior dragStartBehavior;
+  DragGestureRecognizer({ Object debugOwner }) : super(debugOwner: debugOwner);
 
   /// A pointer has contacted the screen and might begin to move.
   ///
@@ -91,11 +60,6 @@
   ///
   /// The position of the pointer is provided in the callback's `details`
   /// argument, which is a [DragStartDetails] object.
-  ///
-  /// Depending on the value of [dragStartBehavior], this function will be
-  /// called on the initial touch down, if set to [DragStartBehavior.down] or
-  /// when the drag gesture is first detected, if set to
-  /// [DragStartBehavior.start].
   GestureDragStartCallback onStart;
 
   /// A pointer that is in contact with the screen and moving has moved again.
@@ -199,16 +163,6 @@
       _state = _DragState.accepted;
       final Offset delta = _pendingDragOffset;
       final Duration timestamp = _lastPendingEventTimestamp;
-      Offset updateDelta;
-      switch (dragStartBehavior) {
-        case DragStartBehavior.start:
-          _initialPosition = _initialPosition + delta;
-          updateDelta = Offset.zero;
-          break;
-        case DragStartBehavior.down:
-          updateDelta = _getDeltaForDetails(delta);
-          break;
-      }
       _pendingDragOffset = Offset.zero;
       _lastPendingEventTimestamp = null;
       if (onStart != null) {
@@ -217,12 +171,13 @@
           globalPosition: _initialPosition,
         )));
       }
-      if (updateDelta != Offset.zero && onUpdate != null) {
+      if (delta != Offset.zero && onUpdate != null) {
+        final Offset deltaForDetails = _getDeltaForDetails(delta);
         invokeCallback<void>('onUpdate', () => onUpdate(DragUpdateDetails(
           sourceTimeStamp: timestamp,
-          delta: updateDelta,
-          primaryDelta: _getPrimaryValueFromOffset(updateDelta),
-          globalPosition: _initialPosition + updateDelta, // Only adds delta for down behaviour
+          delta: deltaForDetails,
+          primaryDelta: _getPrimaryValueFromOffset(delta),
+          globalPosition: _initialPosition + deltaForDetails,
         )));
       }
     }
@@ -277,11 +232,6 @@
     _velocityTrackers.clear();
     super.dispose();
   }
-  @override
-  void debugFillProperties(DiagnosticPropertiesBuilder properties) {
-    super.debugFillProperties(properties);
-    properties.add(EnumProperty<DragStartBehavior>('Start Behavior', dragStartBehavior));
-  }
 }
 
 /// Recognizes movement in the vertical direction.
@@ -330,8 +280,7 @@
 ///    track each touch point independently.
 class HorizontalDragGestureRecognizer extends DragGestureRecognizer {
   /// Create a gesture recognizer for interactions in the horizontal axis.
-  HorizontalDragGestureRecognizer({ Object debugOwner }) :
-        super(debugOwner: debugOwner);
+  HorizontalDragGestureRecognizer({ Object debugOwner }) : super(debugOwner: debugOwner);
 
   @override
   bool _isFlingGesture(VelocityEstimate estimate) {

diff --git a/packages/flutter/lib/src/gestures/recognizer.dart b/packages/flutter/lib/src/gestures/recognizer.dart
index d5ddbd6..ca71a26 100644
--- a/packages/flutter/lib/src/gestures/recognizer.dart
+++ b/packages/flutter/lib/src/gestures/recognizer.dart

@@ -24,24 +24,6 @@
 /// anonymous functions that return objects of particular types.
 typedef RecognizerCallback<T> = T Function();
 
-/// Configuration of offset passed to [DragStartDetails].
-///
-/// The settings determines when a drag formally starts when the user
-/// initiates a drag.
-///
-/// See also:
-///
-///   * [DragGestureRecognizer.dragStartBehavior], which gives an example for the different behaviors.
-enum DragStartBehavior {
-  /// Set the initial offset, at the position where the first down even was
-  /// detected.
-  down,
-
-  /// Set the initial position at the position where the drag start event was
-  /// detected.
-  start,
-}
-
 /// The base class that all gesture recognizers inherit from.
 ///
 /// Provides a basic API that can be used by classes that work with

diff --git a/packages/flutter/lib/src/material/date_picker.dart b/packages/flutter/lib/src/material/date_picker.dart
index 908a43a..12261cc 100644
--- a/packages/flutter/lib/src/material/date_picker.dart
+++ b/packages/flutter/lib/src/material/date_picker.dart

@@ -8,7 +8,6 @@
 import 'package:flutter/rendering.dart';
 import 'package:flutter/services.dart';
 import 'package:flutter/widgets.dart';
-import 'package:flutter/gestures.dart' show DragStartBehavior;
 
 import 'button_bar.dart';
 import 'button_theme.dart';
@@ -251,12 +250,10 @@
     @required this.lastDate,
     @required this.displayedMonth,
     this.selectableDayPredicate,
-    this.dragStartBehavior = DragStartBehavior.start,
   }) : assert(selectedDate != null),
        assert(currentDate != null),
        assert(onChanged != null),
        assert(displayedMonth != null),
-       assert(dragStartBehavior != null),
        assert(!firstDate.isAfter(lastDate)),
        assert(selectedDate.isAfter(firstDate) || selectedDate.isAtSameMomentAs(firstDate)),
        super(key: key);
@@ -284,13 +281,6 @@
   /// Optional user supplied predicate function to customize selectable days.
   final SelectableDayPredicate selectableDayPredicate;
 
-  /// The initial drag behavior of the date picker wheel.
-  ///
-  /// If set to [DragStartBehavior.start], picker drag behavior will begin upon the
-  /// drag gesture winning the arena. If set to [DragStartBehavior.down] it will
-  /// begin when a down event is first detected.
-  final DragStartBehavior dragStartBehavior;
-
   /// Builds widgets showing abbreviated days of week. The first widget in the
   /// returned list corresponds to the first day of week for the current locale.
   ///
@@ -452,7 +442,6 @@
               onChanged(dayToBuild);
             },
             child: dayWidget,
-            dragStartBehavior: dragStartBehavior,
           );
         }
 
@@ -513,7 +502,6 @@
     @required this.firstDate,
     @required this.lastDate,
     this.selectableDayPredicate,
-    this.dragStartBehavior = DragStartBehavior.start,
   }) : assert(selectedDate != null),
        assert(onChanged != null),
        assert(!firstDate.isAfter(lastDate)),
@@ -537,9 +525,6 @@
   /// Optional user supplied predicate function to customize selectable days.
   final SelectableDayPredicate selectableDayPredicate;
 
-  /// {@macro flutter.widgets.scrollable.dragStartBehavior}
-  final DragStartBehavior dragStartBehavior;
-
   @override
   _MonthPickerState createState() => _MonthPickerState();
 }
@@ -624,7 +609,6 @@
       lastDate: widget.lastDate,
       displayedMonth: month,
       selectableDayPredicate: widget.selectableDayPredicate,
-      dragStartBehavior: widget.dragStartBehavior,
     );
   }
 
@@ -685,7 +669,6 @@
                   return false;
                 },
                 child: PageView.builder(
-                  dragStartBehavior: widget.dragStartBehavior,
                   key: ValueKey<DateTime>(widget.selectedDate),
                   controller: _dayPickerController,
                   scrollDirection: Axis.horizontal,
@@ -776,7 +759,6 @@
     @required this.onChanged,
     @required this.firstDate,
     @required this.lastDate,
-    this.dragStartBehavior = DragStartBehavior.start,
   }) : assert(selectedDate != null),
        assert(onChanged != null),
        assert(!firstDate.isAfter(lastDate)),
@@ -796,9 +778,6 @@
   /// The latest date the user is permitted to pick.
   final DateTime lastDate;
 
-  /// {@macro flutter.widgets.scrollable.dragStartBehavior}
-  final DragStartBehavior dragStartBehavior;
-
   @override
   _YearPickerState createState() => _YearPickerState();
 }
@@ -822,7 +801,6 @@
     final ThemeData themeData = Theme.of(context);
     final TextStyle style = themeData.textTheme.body1;
     return ListView.builder(
-      dragStartBehavior: widget.dragStartBehavior,
       controller: scrollController,
       itemExtent: _itemExtent,
       itemCount: widget.lastDate.year - widget.firstDate.year + 1,

diff --git a/packages/flutter/lib/src/material/drawer.dart b/packages/flutter/lib/src/material/drawer.dart
index 6a818e9..89c4e22 100644
--- a/packages/flutter/lib/src/material/drawer.dart
+++ b/packages/flutter/lib/src/material/drawer.dart

@@ -6,7 +6,6 @@
 
 import 'package:flutter/foundation.dart';
 import 'package:flutter/widgets.dart';
-import 'package:flutter/gestures.dart' show DragStartBehavior;
 
 import 'colors.dart';
 import 'debug.dart';
@@ -180,9 +179,7 @@
     @required this.child,
     @required this.alignment,
     this.drawerCallback,
-    this.dragStartBehavior = DragStartBehavior.start,
   }) : assert(child != null),
-       assert(dragStartBehavior != null),
        assert(alignment != null),
        super(key: key);
 
@@ -200,26 +197,6 @@
   /// Optional callback that is called when a [Drawer] is opened or closed.
   final DrawerCallback drawerCallback;
 
-  /// {@template flutter.material.drawer.dragStartBehavior}
-  /// Determines the way that drag start behavior is handled.
-  ///
-  /// If set to [DragStartBehavior.start], the drag behavior used for opening
-  /// and closing a drawer will begin upon the detection of a drag gesture. If
-  /// set to [DragStartBehavior.down] it will begin when a down event is first
-  /// detected.
-  ///
-  /// In general, setting this to [DragStartBehavior.start] will make drag
-  /// animation smoother and setting it to [DragStartBehavior.down] will make
-  /// drag behavior feel slightly more reactive.
-  ///
-  /// By default, the drag start behavior is [DragStartBehavior.start].
-  ///
-  /// See also:
-  ///
-  ///  * [DragGestureRecognizer.dragStartBehavior], which gives an example for the different behaviors.
-  /// {@endtemplate}
-  final DragStartBehavior dragStartBehavior;
-
   @override
   DrawerControllerState createState() => DrawerControllerState();
 }
@@ -422,7 +399,6 @@
           onHorizontalDragEnd: _settle,
           behavior: HitTestBehavior.translucent,
           excludeFromSemantics: true,
-          dragStartBehavior: widget.dragStartBehavior,
           child: Container(width: dragAreaWidth),
         ),
       );
@@ -434,7 +410,6 @@
         onHorizontalDragEnd: _settle,
         onHorizontalDragCancel: _handleDragCancel,
         excludeFromSemantics: true,
-        dragStartBehavior: widget.dragStartBehavior,
         child: RepaintBoundary(
           child: Stack(
             children: <Widget>[

diff --git a/packages/flutter/lib/src/material/paginated_data_table.dart b/packages/flutter/lib/src/material/paginated_data_table.dart
index cfd0b4c..792eec9 100644
--- a/packages/flutter/lib/src/material/paginated_data_table.dart
+++ b/packages/flutter/lib/src/material/paginated_data_table.dart

@@ -6,7 +6,6 @@
 
 import 'package:flutter/widgets.dart';
 import 'package:flutter/rendering.dart';
-import 'package:flutter/gestures.dart' show DragStartBehavior;
 
 import 'button_bar.dart';
 import 'button_theme.dart';
@@ -75,11 +74,9 @@
     this.rowsPerPage = defaultRowsPerPage,
     this.availableRowsPerPage = const <int>[defaultRowsPerPage, defaultRowsPerPage * 2, defaultRowsPerPage * 5, defaultRowsPerPage * 10],
     this.onRowsPerPageChanged,
-    this.dragStartBehavior = DragStartBehavior.start,
     @required this.source
   }) : assert(header != null),
        assert(columns != null),
-       assert(dragStartBehavior != null),
        assert(columns.isNotEmpty),
        assert(sortColumnIndex == null || (sortColumnIndex >= 0 && sortColumnIndex < columns.length)),
        assert(sortAscending != null),
@@ -173,9 +170,6 @@
   /// [PaginatedDataTable] constructor is called.
   final DataTableSource source;
 
-  /// {@macro flutter.widgets.scrollable.dragStartBehavior}
-  final DragStartBehavior dragStartBehavior;
-
   @override
   PaginatedDataTableState createState() => PaginatedDataTableState();
 }
@@ -423,7 +417,6 @@
           ),
           SingleChildScrollView(
             scrollDirection: Axis.horizontal,
-            dragStartBehavior: widget.dragStartBehavior,
             child: DataTable(
               key: _tableKey,
               columns: widget.columns,
@@ -442,7 +435,6 @@
               child: Container(
                 height: 56.0,
                 child: SingleChildScrollView(
-                  dragStartBehavior: widget.dragStartBehavior,
                   scrollDirection: Axis.horizontal,
                   reverse: true,
                   child: Row(

diff --git a/packages/flutter/lib/src/material/scaffold.dart b/packages/flutter/lib/src/material/scaffold.dart
index 7969a86..baba3ac 100644
--- a/packages/flutter/lib/src/material/scaffold.dart
+++ b/packages/flutter/lib/src/material/scaffold.dart

@@ -10,7 +10,6 @@
 import 'package:flutter/rendering.dart';
 import 'package:flutter/scheduler.dart';
 import 'package:flutter/widgets.dart';
-import 'package:flutter/gestures.dart' show DragStartBehavior;
 
 import 'app_bar.dart';
 import 'bottom_sheet.dart';
@@ -733,10 +732,7 @@
     this.backgroundColor,
     this.resizeToAvoidBottomPadding = true,
     this.primary = true,
-    this.drawerDragStartBehavior = DragStartBehavior.start,
-  }) : assert(primary != null),
-       assert(drawerDragStartBehavior != null),
-       super(key: key);
+  }) : assert(primary != null), super(key: key);
 
   /// An app bar to display at the top of the scaffold.
   final PreferredSizeWidget appBar;
@@ -869,9 +865,6 @@
   /// [AppBar.primary], is true.
   final bool primary;
 
-  /// {@macro flutter.material.drawer.dragStartBehavior}
-  final DragStartBehavior drawerDragStartBehavior;
-
   /// The state from the closest instance of this class that encloses the given context.
   ///
   /// Typical usage is as follows:
@@ -1507,7 +1500,6 @@
           alignment: DrawerAlignment.end,
           child: widget.endDrawer,
           drawerCallback: _endDrawerOpenedCallback,
-          dragStartBehavior: widget.drawerDragStartBehavior,
         ),
         _ScaffoldSlot.endDrawer,
         // remove the side padding from the side we're not touching
@@ -1529,7 +1521,6 @@
           alignment: DrawerAlignment.start,
           child: widget.drawer,
           drawerCallback: _drawerOpenedCallback,
-          dragStartBehavior: widget.drawerDragStartBehavior,
         ),
         _ScaffoldSlot.drawer,
         // remove the side padding from the side we're not touching

diff --git a/packages/flutter/lib/src/material/switch.dart b/packages/flutter/lib/src/material/switch.dart
index 183d286..6bc832c 100644
--- a/packages/flutter/lib/src/material/switch.dart
+++ b/packages/flutter/lib/src/material/switch.dart

@@ -73,9 +73,7 @@
     this.activeThumbImage,
     this.inactiveThumbImage,
     this.materialTapTargetSize,
-    this.dragStartBehavior = DragStartBehavior.start,
   }) : _switchType = _SwitchType.material,
-       assert(dragStartBehavior != null),
        super(key: key);
 
   /// Creates a [CupertinoSwitch] if the target platform is iOS, creates a
@@ -97,7 +95,6 @@
     this.activeThumbImage,
     this.inactiveThumbImage,
     this.materialTapTargetSize,
-    this.dragStartBehavior = DragStartBehavior.start,
   }) : _switchType = _SwitchType.adaptive,
        super(key: key);
 
@@ -177,9 +174,6 @@
 
   final _SwitchType _switchType;
 
-  /// {@macro flutter.cupertino.switch.dragStartBehavior}
-  final DragStartBehavior dragStartBehavior;
-
   @override
   _SwitchState createState() => _SwitchState();
 
@@ -225,7 +219,6 @@
     }
 
     return _SwitchRenderObjectWidget(
-      dragStartBehavior: widget.dragStartBehavior,
       value: widget.value,
       activeColor: activeThumbColor,
       inactiveColor: inactiveThumbColor,
@@ -247,7 +240,6 @@
       height: size.height,
       alignment: Alignment.center,
       child: CupertinoSwitch(
-        dragStartBehavior: widget.dragStartBehavior,
         value: widget.value,
         onChanged: widget.onChanged,
         activeColor: widget.activeColor,
@@ -292,7 +284,6 @@
     this.onChanged,
     this.vsync,
     this.additionalConstraints,
-    this.dragStartBehavior,
   }) : super(key: key);
 
   final bool value;
@@ -306,12 +297,10 @@
   final ValueChanged<bool> onChanged;
   final TickerProvider vsync;
   final BoxConstraints additionalConstraints;
-  final DragStartBehavior dragStartBehavior;
 
   @override
   _RenderSwitch createRenderObject(BuildContext context) {
     return _RenderSwitch(
-      dragStartBehavior: dragStartBehavior,
       value: value,
       activeColor: activeColor,
       inactiveColor: inactiveColor,
@@ -341,7 +330,6 @@
       ..onChanged = onChanged
       ..textDirection = Directionality.of(context)
       ..additionalConstraints = additionalConstraints
-      ..dragStartBehavior = dragStartBehavior
       ..vsync = vsync;
   }
 }
@@ -360,7 +348,6 @@
     @required TextDirection textDirection,
     ValueChanged<bool> onChanged,
     @required TickerProvider vsync,
-    DragStartBehavior dragStartBehavior,
   }) : assert(textDirection != null),
        _activeThumbImage = activeThumbImage,
        _inactiveThumbImage = inactiveThumbImage,
@@ -380,8 +367,7 @@
     _drag = HorizontalDragGestureRecognizer()
       ..onStart = _handleDragStart
       ..onUpdate = _handleDragUpdate
-      ..onEnd = _handleDragEnd
-      ..dragStartBehavior = dragStartBehavior;
+      ..onEnd = _handleDragEnd;
   }
 
   ImageProvider get activeThumbImage => _activeThumbImage;
@@ -442,14 +428,6 @@
     markNeedsPaint();
   }
 
-  DragStartBehavior get dragStartBehavior => _drag.dragStartBehavior;
-  set dragStartBehavior(DragStartBehavior value) {
-    assert(value != null);
-    if(_drag.dragStartBehavior == value)
-      return;
-    _drag.dragStartBehavior = value;
-  }
-
   @override
   void detach() {
     _cachedThumbPainter?.dispose();

diff --git a/packages/flutter/lib/src/material/tabs.dart b/packages/flutter/lib/src/material/tabs.dart
index 7940579..f83130e 100644
--- a/packages/flutter/lib/src/material/tabs.dart
+++ b/packages/flutter/lib/src/material/tabs.dart

@@ -7,7 +7,6 @@
 
 import 'package:flutter/rendering.dart';
 import 'package:flutter/widgets.dart';
-import 'package:flutter/gestures.dart' show DragStartBehavior;
 
 import 'app_bar.dart';
 import 'colors.dart';
@@ -550,11 +549,9 @@
     this.labelPadding,
     this.unselectedLabelColor,
     this.unselectedLabelStyle,
-    this.dragStartBehavior = DragStartBehavior.start,
     this.onTap,
   }) : assert(tabs != null),
        assert(isScrollable != null),
-       assert(dragStartBehavior != null),
        assert(indicator != null || (indicatorWeight != null && indicatorWeight > 0.0)),
        assert(indicator != null || (indicatorPadding != null)),
        super(key: key);
@@ -665,9 +662,6 @@
   /// is null then the text style of the theme's body2 definition is used.
   final TextStyle unselectedLabelStyle;
 
-  /// {@macro flutter.widgets.scrollable.dragStartBehavior}
-  final DragStartBehavior dragStartBehavior;
-
   /// An optional callback that's called when the [TabBar] is tapped.
   ///
   /// The callback is applied to the index of the tab where the tap occurred.
@@ -1017,7 +1011,6 @@
     if (widget.isScrollable) {
       _scrollController ??= _TabBarScrollController(this);
       tabBar = SingleChildScrollView(
-        dragStartBehavior: widget.dragStartBehavior,
         scrollDirection: Axis.horizontal,
         controller: _scrollController,
         child: tabBar,
@@ -1042,10 +1035,7 @@
     @required this.children,
     this.controller,
     this.physics,
-    this.dragStartBehavior = DragStartBehavior.start,
-  }) : assert(children != null),
-       assert(dragStartBehavior != null),
-       super(key: key);
+  }) : assert(children != null), super(key: key);
 
   /// This widget's selection and animation state.
   ///
@@ -1067,9 +1057,6 @@
   /// Defaults to matching platform conventions.
   final ScrollPhysics physics;
 
-  /// {@macro flutter.widgets.scrollable.dragStartBehavior}
-  final DragStartBehavior dragStartBehavior;
-
   @override
   _TabBarViewState createState() => _TabBarViewState();
 }
@@ -1214,7 +1201,6 @@
     return NotificationListener<ScrollNotification>(
       onNotification: _handleScrollNotification,
       child: PageView(
-        dragStartBehavior: widget.dragStartBehavior,
         controller: _pageController,
         physics: widget.physics == null ? _kTabBarViewPhysics : _kTabBarViewPhysics.applyTo(widget.physics),
         children: _children,

diff --git a/packages/flutter/lib/src/material/text_field.dart b/packages/flutter/lib/src/material/text_field.dart
index d5e374f..4ca47e4 100644
--- a/packages/flutter/lib/src/material/text_field.dart
+++ b/packages/flutter/lib/src/material/text_field.dart

@@ -8,7 +8,6 @@
 import 'package:flutter/rendering.dart';
 import 'package:flutter/services.dart';
 import 'package:flutter/widgets.dart';
-import 'package:flutter/gestures.dart';
 
 import 'debug.dart';
 import 'feedback.dart';
@@ -128,7 +127,6 @@
     this.cursorColor,
     this.keyboardAppearance,
     this.scrollPadding = const EdgeInsets.all(20.0),
-    this.dragStartBehavior = DragStartBehavior.start,
     this.enableInteractiveSelection,
     this.onTap,
   }) : assert(textAlign != null),
@@ -137,7 +135,6 @@
        assert(autocorrect != null),
        assert(maxLengthEnforced != null),
        assert(scrollPadding != null),
-       assert(dragStartBehavior != null),
        assert(maxLines == null || maxLines > 0),
        assert(maxLength == null || maxLength == TextField.noMaxLength || maxLength > 0),
        keyboardType = keyboardType ?? (maxLines == 1 ? TextInputType.text : TextInputType.multiline),
@@ -349,9 +346,6 @@
   /// {@macro flutter.widgets.editableText.enableInteractiveSelection}
   final bool enableInteractiveSelection;
 
-  /// {@macro flutter.widgets.scrollable.dragStartBehavior}
-  final DragStartBehavior dragStartBehavior;
-
   /// {@macro flutter.rendering.editable.selectionEnabled}
   bool get selectionEnabled {
     return enableInteractiveSelection ?? !obscureText;
@@ -675,7 +669,6 @@
         scrollPadding: widget.scrollPadding,
         keyboardAppearance: keyboardAppearance,
         enableInteractiveSelection: widget.enableInteractiveSelection,
-        dragStartBehavior: widget.dragStartBehavior,
       ),
     );
 

diff --git a/packages/flutter/lib/src/widgets/dismissible.dart b/packages/flutter/lib/src/widgets/dismissible.dart
index 98a94b7..f945da4 100644
--- a/packages/flutter/lib/src/widgets/dismissible.dart
+++ b/packages/flutter/lib/src/widgets/dismissible.dart

@@ -2,8 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-import 'package:flutter/gestures.dart';
-
 import 'automatic_keep_alive.dart';
 import 'basic.dart';
 import 'debug.dart';
@@ -84,10 +82,8 @@
     this.dismissThresholds = const <DismissDirection, double>{},
     this.movementDuration = const Duration(milliseconds: 200),
     this.crossAxisEndOffset = 0.0,
-    this.dragStartBehavior = DragStartBehavior.start,
   }) : assert(key != null),
        assert(secondaryBackground != null ? background != null : true),
-       assert(dragStartBehavior != null),
        super(key: key);
 
   /// The widget below this widget in the tree.
@@ -146,23 +142,6 @@
   /// it is positive or negative.
   final double crossAxisEndOffset;
 
-  /// Determines the way that drag start behavior is handled.
-  ///
-  /// If set to [DragStartBehavior.start], the drag gesture used to dismiss a
-  /// dismissible will begin upon the detection of a drag gesture. If set to
-  /// [DragStartBehavior.down] it will begin when a down event is first detected.
-  ///
-  /// In general, setting this to [DragStartBehavior.start] will make drag
-  /// animation smoother and setting it to [DragStartBehavior.down] will make
-  /// drag behavior feel slightly more reactive.
-  ///
-  /// By default, the drag start behavior is [DragStartBehavior.start].
-  ///
-  /// See also:
-  ///
-  ///  * [DragGestureRecognizer.dragStartBehavior], which gives an example for the different behaviors.
-  final DragStartBehavior dragStartBehavior;
-
   @override
   _DismissibleState createState() => _DismissibleState();
 }
@@ -348,8 +327,8 @@
       Tween<Offset>(
         begin: Offset.zero,
         end: _directionIsXAxis
-            ? Offset(end, widget.crossAxisEndOffset)
-            : Offset(widget.crossAxisEndOffset, end),
+               ? Offset(end, widget.crossAxisEndOffset)
+               : Offset(widget.crossAxisEndOffset, end),
       ),
     );
   }
@@ -535,6 +514,7 @@
       children.add(content);
       content = Stack(children: children);
     }
+
     // We are not resizing but we may be being dragging in widget.direction.
     return GestureDetector(
       onHorizontalDragStart: _directionIsXAxis ? _handleDragStart : null,
@@ -544,8 +524,7 @@
       onVerticalDragUpdate: _directionIsXAxis ? null : _handleDragUpdate,
       onVerticalDragEnd: _directionIsXAxis ? null : _handleDragEnd,
       behavior: HitTestBehavior.opaque,
-      child: content,
-      dragStartBehavior: widget.dragStartBehavior,
+      child: content
     );
   }
 }

diff --git a/packages/flutter/lib/src/widgets/editable_text.dart b/packages/flutter/lib/src/widgets/editable_text.dart
index c8dc527..bd22473 100644
--- a/packages/flutter/lib/src/widgets/editable_text.dart
+++ b/packages/flutter/lib/src/widgets/editable_text.dart

@@ -8,7 +8,6 @@
 import 'package:flutter/rendering.dart';
 import 'package:flutter/scheduler.dart';
 import 'package:flutter/services.dart';
-import 'package:flutter/gestures.dart' show DragStartBehavior;
 
 import 'automatic_keep_alive.dart';
 import 'basic.dart';
@@ -185,8 +184,7 @@
   /// default to [TextInputType.multiline].
   ///
   /// The [controller], [focusNode], [style], [cursorColor], [backgroundCursorColor],
-  /// [textAlign], [dragStartBehavior] and [rendererIgnoresPointer] arguments
-  /// must not be null.
+  /// [textAlign], and [rendererIgnoresPointer] arguments must not be null.
   EditableText({
     Key key,
     @required this.controller,
@@ -217,7 +215,6 @@
     this.cursorRadius,
     this.scrollPadding = const EdgeInsets.all(20.0),
     this.keyboardAppearance = Brightness.light,
-    this.dragStartBehavior = DragStartBehavior.start,
     this.enableInteractiveSelection,
   }) : assert(controller != null),
        assert(focusNode != null),
@@ -231,7 +228,6 @@
        assert(autofocus != null),
        assert(rendererIgnoresPointer != null),
        assert(scrollPadding != null),
-       assert(dragStartBehavior != null),
        keyboardType = keyboardType ?? (maxLines == 1 ? TextInputType.text : TextInputType.multiline),
        inputFormatters = maxLines == 1
            ? (
@@ -288,10 +284,6 @@
   /// its left.
   ///
   /// Defaults to the ambient [Directionality], if any.
-  ///
-  /// See also:
-  ///
-  ///   * {@macro flutter.gestures.monodrag.dragStartExample}
   /// {@endtemplate}
   final TextDirection textDirection;
 
@@ -502,9 +494,6 @@
   /// Defaults to false, resulting in a typical blinking cursor.
   static bool debugDeterministicCursor = false;
 
-  /// {@macro flutter.widgets.scrollable.dragStartBehavior}
-  final DragStartBehavior dragStartBehavior;
-
   /// {@macro flutter.rendering.editable.selectionEnabled}
   bool get selectionEnabled {
     return enableInteractiveSelection ?? !obscureText;
@@ -851,7 +840,6 @@
         renderObject: renderObject,
         selectionControls: widget.selectionControls,
         selectionDelegate: this,
-        dragStartBehavior: widget.dragStartBehavior,
       );
       final bool longPress = cause == SelectionChangedCause.longPress;
       if (cause != SelectionChangedCause.keyboard && (_value.text.isNotEmpty || longPress))
@@ -1073,7 +1061,6 @@
       axisDirection: _isMultiline ? AxisDirection.down : AxisDirection.right,
       controller: _scrollController,
       physics: const ClampingScrollPhysics(),
-      dragStartBehavior: widget.dragStartBehavior,
       viewportBuilder: (BuildContext context, ViewportOffset offset) {
         return CompositedTransformTarget(
           link: _layerLink,

diff --git a/packages/flutter/lib/src/widgets/gesture_detector.dart b/packages/flutter/lib/src/widgets/gesture_detector.dart
index de41403..158d308 100644
--- a/packages/flutter/lib/src/widgets/gesture_detector.dart
+++ b/packages/flutter/lib/src/widgets/gesture_detector.dart

@@ -184,10 +184,8 @@
     this.onScaleUpdate,
     this.onScaleEnd,
     this.behavior,
-    this.excludeFromSemantics = false,
-    this.dragStartBehavior = DragStartBehavior.start,
+    this.excludeFromSemantics = false
   }) : assert(excludeFromSemantics != null),
-       assert(dragStartBehavior != null),
        assert(() {
          final bool haveVerticalDrag = onVerticalDragStart != null || onVerticalDragUpdate != null || onVerticalDragEnd != null;
          final bool haveHorizontalDrag = onHorizontalDragStart != null || onHorizontalDragUpdate != null || onHorizontalDragEnd != null;
@@ -372,23 +370,6 @@
   /// duplication of information.
   final bool excludeFromSemantics;
 
-  /// Determines the way that drag start behavior is handled.
-  ///
-  /// If set to [DragStartBehavior.start], gesture drag behavior will
-  /// begin upon the detection of a drag gesture. If set to
-  /// [DragStartBehavior.down] it will begin when a down event is first detected.
-  ///
-  /// In general, setting this to [DragStartBehavior.start] will make drag
-  /// animation smoother and setting it to [DragStartBehavior.down] will make
-  /// drag behavior feel slightly more reactive.
-  ///
-  /// By default, the drag start behavior is [DragStartBehavior.start].
-  ///
-  /// See also:
-  ///
-  ///  * [DragGestureRecognizer.dragStartBehavior], which gives an example for the different behaviors.
-  final DragStartBehavior dragStartBehavior;
-
   @override
   Widget build(BuildContext context) {
     final Map<Type, GestureRecognizerFactory> gestures = <Type, GestureRecognizerFactory>{};
@@ -440,8 +421,7 @@
             ..onStart = onVerticalDragStart
             ..onUpdate = onVerticalDragUpdate
             ..onEnd = onVerticalDragEnd
-            ..onCancel = onVerticalDragCancel
-            ..dragStartBehavior = dragStartBehavior;
+            ..onCancel = onVerticalDragCancel;
         },
       );
     }
@@ -459,8 +439,7 @@
             ..onStart = onHorizontalDragStart
             ..onUpdate = onHorizontalDragUpdate
             ..onEnd = onHorizontalDragEnd
-            ..onCancel = onHorizontalDragCancel
-            ..dragStartBehavior = dragStartBehavior;
+            ..onCancel = onHorizontalDragCancel;
         },
       );
     }
@@ -478,8 +457,7 @@
             ..onStart = onPanStart
             ..onUpdate = onPanUpdate
             ..onEnd = onPanEnd
-            ..onCancel = onPanCancel
-            ..dragStartBehavior = dragStartBehavior;
+            ..onCancel = onPanCancel;
         },
       );
     }
@@ -519,11 +497,6 @@
       child: child,
     );
   }
-  @override
-  void debugFillProperties(DiagnosticPropertiesBuilder properties) {
-    super.debugFillProperties(properties);
-    properties.add(EnumProperty<DragStartBehavior>('startBehavior', dragStartBehavior));
-  }
 }
 
 /// A widget that detects gestures described by the given gesture
@@ -577,7 +550,7 @@
     this.child,
     this.gestures = const <Type, GestureRecognizerFactory>{},
     this.behavior,
-    this.excludeFromSemantics = false,
+    this.excludeFromSemantics = false
   }) : assert(gestures != null),
        assert(excludeFromSemantics != null),
        super(key: key);

diff --git a/packages/flutter/lib/src/widgets/nested_scroll_view.dart b/packages/flutter/lib/src/widgets/nested_scroll_view.dart
index 4369334..8d41074 100644
--- a/packages/flutter/lib/src/widgets/nested_scroll_view.dart
+++ b/packages/flutter/lib/src/widgets/nested_scroll_view.dart

@@ -10,7 +10,6 @@
 import 'package:flutter/physics.dart';
 import 'package:flutter/rendering.dart';
 import 'package:flutter/scheduler.dart';
-import 'package:flutter/gestures.dart' show DragStartBehavior;
 
 import 'basic.dart';
 import 'framework.dart';
@@ -52,7 +51,7 @@
 /// in the opposite direction (e.g. allowing the user to swipe horizontally
 /// between the pages represented by the tabs, while the list scrolls
 /// vertically), then any list inside that [TabBarView] would not interact with
-/// the outer [ScrollView]. For example, flinginsg the inner list to scroll to
+/// the outer [ScrollView]. For example, flinging the inner list to scroll to
 /// the top would not cause a collapsed [SliverAppBar] in the outer [ScrollView]
 /// to expand.
 ///
@@ -189,7 +188,6 @@
     this.physics,
     @required this.headerSliverBuilder,
     @required this.body,
-    this.dragStartBehavior = DragStartBehavior.start,
   }) : assert(scrollDirection != null),
        assert(reverse != null),
        assert(headerSliverBuilder != null),
@@ -254,9 +252,6 @@
   /// the [PrimaryScrollController] provided by the [NestedScrollView].
   final Widget body;
 
-  /// {@macro flutter.widgets.scrollable.dragStartBehavior}
-  final DragStartBehavior dragStartBehavior;
-
   /// Returns the [SliverOverlapAbsorberHandle] of the nearest ancestor
   /// [NestedScrollView].
   ///
@@ -343,7 +338,6 @@
         builder: (BuildContext context) {
           _lastHasScrolledBody = _coordinator.hasScrolledBody;
           return _NestedScrollViewCustomScrollView(
-            dragStartBehavior: widget.dragStartBehavior,
             scrollDirection: widget.scrollDirection,
             reverse: widget.reverse,
             physics: widget.physics != null
@@ -371,14 +365,12 @@
     @required ScrollController controller,
     @required List<Widget> slivers,
     @required this.handle,
-    DragStartBehavior dragStartBehavior = DragStartBehavior.start,
   }) : super(
          scrollDirection: scrollDirection,
          reverse: reverse,
          physics: physics,
          controller: controller,
          slivers: slivers,
-         dragStartBehavior: dragStartBehavior,
        );
 
   final SliverOverlapAbsorberHandle handle;

diff --git a/packages/flutter/lib/src/widgets/page_view.dart b/packages/flutter/lib/src/widgets/page_view.dart
index a46f22e..371cd58 100644
--- a/packages/flutter/lib/src/widgets/page_view.dart
+++ b/packages/flutter/lib/src/widgets/page_view.dart

@@ -7,7 +7,6 @@
 
 import 'package:flutter/physics.dart';
 import 'package:flutter/rendering.dart';
-import 'package:flutter/gestures.dart' show DragStartBehavior;
 
 import 'basic.dart';
 import 'debug.dart';
@@ -424,7 +423,6 @@
     this.pageSnapping = true,
     this.onPageChanged,
     List<Widget> children = const <Widget>[],
-    this.dragStartBehavior = DragStartBehavior.start,
   }) : controller = controller ?? _defaultPageController,
        childrenDelegate = SliverChildListDelegate(children),
        super(key: key);
@@ -451,7 +449,6 @@
     this.onPageChanged,
     @required IndexedWidgetBuilder itemBuilder,
     int itemCount,
-    this.dragStartBehavior = DragStartBehavior.start,
   }) : controller = controller ?? _defaultPageController,
        childrenDelegate = SliverChildBuilderDelegate(itemBuilder, childCount: itemCount),
        super(key: key);
@@ -467,7 +464,6 @@
     this.pageSnapping = true,
     this.onPageChanged,
     @required this.childrenDelegate,
-    this.dragStartBehavior = DragStartBehavior.start,
   }) : assert(childrenDelegate != null),
        controller = controller ?? _defaultPageController,
        super(key: key);
@@ -520,9 +516,6 @@
   /// respectively.
   final SliverChildDelegate childrenDelegate;
 
-  /// {@macro flutter.widgets.scrollable.dragStartBehavior}
-  final DragStartBehavior dragStartBehavior;
-
   @override
   _PageViewState createState() => _PageViewState();
 }
@@ -569,7 +562,6 @@
         return false;
       },
       child: Scrollable(
-        dragStartBehavior: widget.dragStartBehavior,
         axisDirection: axisDirection,
         controller: widget.controller,
         physics: physics,

diff --git a/packages/flutter/lib/src/widgets/scroll_view.dart b/packages/flutter/lib/src/widgets/scroll_view.dart
index 7e701a5..f4575e6 100644
--- a/packages/flutter/lib/src/widgets/scroll_view.dart
+++ b/packages/flutter/lib/src/widgets/scroll_view.dart

@@ -5,7 +5,6 @@
 import 'dart:math' as math;
 
 import 'package:flutter/rendering.dart';
-import 'package:flutter/gestures.dart';
 
 import 'basic.dart';
 import 'framework.dart';
@@ -61,10 +60,8 @@
     this.shrinkWrap = false,
     this.cacheExtent,
     this.semanticChildCount,
-    this.dragStartBehavior = DragStartBehavior.start,
   }) : assert(reverse != null),
        assert(shrinkWrap != null),
-       assert(dragStartBehavior != null),
        assert(!(controller != null && primary == true),
            'Primary ScrollViews obtain their ScrollController via inheritance from a PrimaryScrollController widget. '
            'You cannot both set primary to true and pass an explicit controller.'
@@ -190,9 +187,6 @@
   ///  * [SemanticsConfiguration.scrollChildCount], the corresponding semantics property.
   final int semanticChildCount;
 
-  /// {@macro flutter.widgets.scrollable.dragStartBehavior}
-  final DragStartBehavior dragStartBehavior;
-
   /// Returns the [AxisDirection] in which the scroll view scrolls.
   ///
   /// Combines the [scrollDirection] with the [reverse] boolean to obtain the
@@ -252,7 +246,6 @@
       ? PrimaryScrollController.of(context)
       : controller;
     final Scrollable scrollable = Scrollable(
-      dragStartBehavior: dragStartBehavior,
       axisDirection: axisDirection,
       controller: scrollController,
       physics: physics,
@@ -404,7 +397,6 @@
     double cacheExtent,
     this.slivers = const <Widget>[],
     int semanticChildCount,
-    DragStartBehavior dragStartBehavior = DragStartBehavior.start,
   }) : super(
     key: key,
     scrollDirection: scrollDirection,
@@ -415,7 +407,6 @@
     shrinkWrap: shrinkWrap,
     cacheExtent: cacheExtent,
     semanticChildCount: semanticChildCount,
-    dragStartBehavior: dragStartBehavior,
   );
 
   /// The slivers to place inside the viewport.
@@ -448,7 +439,6 @@
     this.padding,
     double cacheExtent,
     int semanticChildCount,
-    DragStartBehavior dragStartBehavior = DragStartBehavior.start,
   }) : super(
     key: key,
     scrollDirection: scrollDirection,
@@ -459,7 +449,6 @@
     shrinkWrap: shrinkWrap,
     cacheExtent: cacheExtent,
     semanticChildCount: semanticChildCount,
-    dragStartBehavior: dragStartBehavior,
   );
 
   /// The amount of space by which to inset the children.
@@ -750,7 +739,6 @@
     double cacheExtent,
     List<Widget> children = const <Widget>[],
     int semanticChildCount,
-    DragStartBehavior dragStartBehavior = DragStartBehavior.start,
   }) : childrenDelegate = SliverChildListDelegate(
          children,
          addAutomaticKeepAlives: addAutomaticKeepAlives,
@@ -767,7 +755,6 @@
     padding: padding,
     cacheExtent: cacheExtent,
     semanticChildCount: semanticChildCount ?? children.length,
-    dragStartBehavior: dragStartBehavior,
   );
 
   /// Creates a scrollable, linear array of widgets that are created on demand.
@@ -813,7 +800,6 @@
     bool addSemanticIndexes = true,
     double cacheExtent,
     int semanticChildCount,
-    DragStartBehavior dragStartBehavior = DragStartBehavior.start,
   }) : childrenDelegate = SliverChildBuilderDelegate(
          itemBuilder,
          childCount: itemCount,
@@ -831,7 +817,6 @@
     padding: padding,
     cacheExtent: cacheExtent,
     semanticChildCount: semanticChildCount ?? itemCount,
-    dragStartBehavior: dragStartBehavior,
   );
 
   /// Creates a fixed-length scrollable linear array of list "items" separated
@@ -1265,7 +1250,6 @@
     @required this.childrenDelegate,
     double cacheExtent,
     int semanticChildCount,
-    DragStartBehavior dragStartBehavior = DragStartBehavior.start,
   }) : assert(gridDelegate != null),
        assert(childrenDelegate != null),
        super(
@@ -1279,7 +1263,6 @@
          padding: padding,
          cacheExtent: cacheExtent,
          semanticChildCount: semanticChildCount,
-         dragStartBehavior: dragStartBehavior,
        );
 
   /// Creates a scrollable, 2D array of widgets with a fixed number of tiles in
@@ -1315,7 +1298,6 @@
     double cacheExtent,
     List<Widget> children = const <Widget>[],
     int semanticChildCount,
-    DragStartBehavior dragStartBehavior = DragStartBehavior.start,
   }) : gridDelegate = SliverGridDelegateWithFixedCrossAxisCount(
          crossAxisCount: crossAxisCount,
          mainAxisSpacing: mainAxisSpacing,
@@ -1338,7 +1320,6 @@
     padding: padding,
     cacheExtent: cacheExtent,
     semanticChildCount: semanticChildCount ?? children.length,
-    dragStartBehavior: dragStartBehavior,
   );
 
   /// Creates a scrollable, 2D array of widgets with tiles that each have a
@@ -1373,7 +1354,6 @@
     bool addSemanticIndexes = true,
     List<Widget> children = const <Widget>[],
     int semanticChildCount,
-    DragStartBehavior dragStartBehavior = DragStartBehavior.start,
   }) : gridDelegate = SliverGridDelegateWithMaxCrossAxisExtent(
          maxCrossAxisExtent: maxCrossAxisExtent,
          mainAxisSpacing: mainAxisSpacing,
@@ -1395,7 +1375,6 @@
     shrinkWrap: shrinkWrap,
     padding: padding,
     semanticChildCount: semanticChildCount ?? children.length,
-    dragStartBehavior: dragStartBehavior,
   );
 
   /// A delegate that controls the layout of the children within the [GridView].

diff --git a/packages/flutter/lib/src/widgets/scrollable.dart b/packages/flutter/lib/src/widgets/scrollable.dart
index 42b91a9..d6768c0 100644
--- a/packages/flutter/lib/src/widgets/scrollable.dart
+++ b/packages/flutter/lib/src/widgets/scrollable.dart

@@ -81,9 +81,7 @@
     @required this.viewportBuilder,
     this.excludeFromSemantics = false,
     this.semanticChildCount,
-    this.dragStartBehavior = DragStartBehavior.start,
   }) : assert(axisDirection != null),
-       assert(dragStartBehavior != null),
        assert(viewportBuilder != null),
        assert(excludeFromSemantics != null),
        super (key: key);
@@ -182,25 +180,6 @@
   ///  * [SemanticsConfiguration.scrollChildCount], the corresponding semantics property.
   final int semanticChildCount;
 
-  /// {@template flutter.widgets.scrollable.dragStartBehavior}
-  /// Determines the way that drag start behavior is handled.
-  ///
-  /// If set to [DragStartBehavior.start], scrolling drag behavior will
-  /// begin upon the detection of a drag gesture. If set to
-  /// [DragStartBehavior.down] it will begin when a down event is first detected.
-  ///
-  /// In general, setting this to [DragStartBehavior.start] will make drag
-  /// animation smoother and setting it to [DragStartBehavior.down] will make
-  /// drag behavior feel slightly more reactive.
-  ///
-  /// By default, the drag start behavior is [DragStartBehavior.start].
-  ///
-  /// See also:
-  ///
-  ///  * [DragGestureRecognizer.dragStartBehavior], which gives an example for the different behaviors.
-  /// {@endtemplate}
-  final DragStartBehavior dragStartBehavior;
-
   /// The axis along which the scroll view scrolls.
   ///
   /// Determined by the [axisDirection].
@@ -412,8 +391,7 @@
                   ..onCancel = _handleDragCancel
                   ..minFlingDistance = _physics?.minFlingDistance
                   ..minFlingVelocity = _physics?.minFlingVelocity
-                  ..maxFlingVelocity = _physics?.maxFlingVelocity
-                  ..dragStartBehavior = widget.dragStartBehavior;
+                  ..maxFlingVelocity = _physics?.maxFlingVelocity;
               },
             ),
           };
@@ -431,8 +409,7 @@
                   ..onCancel = _handleDragCancel
                   ..minFlingDistance = _physics?.minFlingDistance
                   ..minFlingVelocity = _physics?.minFlingVelocity
-                  ..maxFlingVelocity = _physics?.maxFlingVelocity
-                  ..dragStartBehavior = widget.dragStartBehavior;
+                  ..maxFlingVelocity = _physics?.maxFlingVelocity;
               },
             ),
           };

diff --git a/packages/flutter/lib/src/widgets/single_child_scroll_view.dart b/packages/flutter/lib/src/widgets/single_child_scroll_view.dart
index dbd0399..2520283 100644
--- a/packages/flutter/lib/src/widgets/single_child_scroll_view.dart
+++ b/packages/flutter/lib/src/widgets/single_child_scroll_view.dart

@@ -5,7 +5,6 @@
 import 'dart:math' as math;
 
 import 'package:flutter/rendering.dart';
-import 'package:flutter/gestures.dart' show DragStartBehavior;
 
 import 'basic.dart';
 import 'framework.dart';
@@ -193,9 +192,7 @@
     this.physics,
     this.controller,
     this.child,
-    this.dragStartBehavior = DragStartBehavior.start,
   }) : assert(scrollDirection != null),
-       assert(dragStartBehavior != null),
        assert(!(controller != null && primary == true),
           'Primary ScrollViews obtain their ScrollController via inheritance from a PrimaryScrollController widget. '
           'You cannot both set primary to true and pass an explicit controller.'
@@ -262,9 +259,6 @@
   /// {@macro flutter.widgets.child}
   final Widget child;
 
-  /// {@macro flutter.widgets.scrollable.dragStartBehavior}
-  final DragStartBehavior dragStartBehavior;
-
   AxisDirection _getDirection(BuildContext context) {
     return getAxisDirectionFromAxisReverseAndDirectionality(context, scrollDirection, reverse);
   }
@@ -279,7 +273,6 @@
         ? PrimaryScrollController.of(context)
         : controller;
     final Scrollable scrollable = Scrollable(
-      dragStartBehavior: dragStartBehavior,
       axisDirection: axisDirection,
       controller: scrollController,
       physics: physics,

diff --git a/packages/flutter/lib/src/widgets/text_selection.dart b/packages/flutter/lib/src/widgets/text_selection.dart
index 5d8110e..7af804f 100644
--- a/packages/flutter/lib/src/widgets/text_selection.dart
+++ b/packages/flutter/lib/src/widgets/text_selection.dart

@@ -8,7 +8,6 @@
 import 'package:flutter/rendering.dart';
 import 'package:flutter/services.dart';
 import 'package:flutter/scheduler.dart';
-import 'package:flutter/gestures.dart' show DragStartBehavior;
 
 import 'basic.dart';
 import 'container.dart';
@@ -230,7 +229,6 @@
     @required this.renderObject,
     this.selectionControls,
     this.selectionDelegate,
-    this.dragStartBehavior = DragStartBehavior.start,
   }): assert(value != null),
       assert(context != null),
       _value = value {
@@ -265,23 +263,6 @@
   /// text field.
   final TextSelectionDelegate selectionDelegate;
 
-  /// Determines the way that drag start behavior is handled.
-  ///
-  /// If set to [DragStartBehavior.start], handle drag behavior will
-  /// begin upon the detection of a drag gesture. If set to
-  /// [DragStartBehavior.down] it will begin when a down event is first detected.
-  ///
-  /// In general, setting this to [DragStartBehavior.start] will make drag
-  /// animation smoother and setting it to [DragStartBehavior.down] will make
-  /// drag behavior feel slightly more reactive.
-  ///
-  /// By default, the drag start behavior is [DragStartBehavior.start].
-  ///
-  /// See also:
-  ///
-  ///  * [DragGestureRecognizer.dragStartBehavior], which gives an example for the different behaviors.
-  final DragStartBehavior dragStartBehavior;
-
   /// Controls the fade-in animations.
   static const Duration _fadeDuration = Duration(milliseconds: 150);
   AnimationController _handleController;
@@ -384,8 +365,9 @@
 
   Widget _buildHandle(BuildContext context, _TextSelectionHandlePosition position) {
     if ((_selection.isCollapsed && position == _TextSelectionHandlePosition.end) ||
-         selectionControls == null)
+        selectionControls == null)
       return Container(); // hide the second handle when collapsed
+
     return FadeTransition(
       opacity: _handleOpacity,
       child: _TextSelectionHandleOverlay(
@@ -396,7 +378,6 @@
         selection: _selection,
         selectionControls: selectionControls,
         position: position,
-        dragStartBehavior: dragStartBehavior,
       )
     );
   }
@@ -466,8 +447,7 @@
     @required this.renderObject,
     @required this.onSelectionHandleChanged,
     @required this.onSelectionHandleTapped,
-    @required this.selectionControls,
-    this.dragStartBehavior = DragStartBehavior.start,
+    @required this.selectionControls
   }) : super(key: key);
 
   final TextSelection selection;
@@ -477,7 +457,6 @@
   final ValueChanged<TextSelection> onSelectionHandleChanged;
   final VoidCallback onSelectionHandleTapped;
   final TextSelectionControls selectionControls;
-  final DragStartBehavior dragStartBehavior;
 
   @override
   _TextSelectionHandleOverlayState createState() => _TextSelectionHandleOverlayState();
@@ -549,7 +528,6 @@
       link: widget.layerLink,
       showWhenUnlinked: false,
       child: GestureDetector(
-        dragStartBehavior: widget.dragStartBehavior,
         onPanStart: _handleDragStart,
         onPanUpdate: _handleDragUpdate,
         onTap: _handleTap,

diff --git a/packages/flutter/test/cupertino/switch_test.dart b/packages/flutter/test/cupertino/switch_test.dart
index 08f4a78..c08ea4a 100644
--- a/packages/flutter/test/cupertino/switch_test.dart
+++ b/packages/flutter/test/cupertino/switch_test.dart

@@ -4,7 +4,6 @@
 
 import 'package:flutter/cupertino.dart';
 import 'package:flutter_test/flutter_test.dart';
-import 'package:flutter/gestures.dart';
 
 void main() {
   testWidgets('Switch can toggle on tap', (WidgetTester tester) async {
@@ -19,7 +18,6 @@
               child: CupertinoSwitch(
                 key: switchKey,
                 value: value,
-                dragStartBehavior: DragStartBehavior.down,
                 onChanged: (bool newValue) {
                   setState(() {
                     value = newValue;
@@ -48,7 +46,6 @@
             return Center(
               child: CupertinoSwitch(
                 value: value,
-                dragStartBehavior: DragStartBehavior.down,
                 onChanged: (bool newValue) {
                   setState(() {
                     value = newValue;
@@ -82,88 +79,6 @@
     expect(value, isFalse);
   });
 
-  testWidgets('Switch can drag with dragStartBehavior', (WidgetTester tester) async {
-    bool value = false;
-
-    await tester.pumpWidget(
-      Directionality(
-        textDirection: TextDirection.ltr,
-        child: StatefulBuilder(
-          builder: (BuildContext context, StateSetter setState) {
-            return Center(
-              child: CupertinoSwitch(
-                value: value,
-                dragStartBehavior: DragStartBehavior.down,
-                onChanged: (bool newValue) {
-                  setState(() {
-                    value = newValue;
-                  });
-                },
-              ),
-            );
-          },
-        ),
-      ),
-    );
-
-    expect(value, isFalse);
-    await tester.drag(find.byType(CupertinoSwitch), const Offset(-30.0, 0.0));
-    expect(value, isFalse);
-
-    await tester.drag(find.byType(CupertinoSwitch), const Offset(30.0, 0.0));
-    expect(value, isTrue);
-    await tester.pump();
-    await tester.drag(find.byType(CupertinoSwitch), const Offset(30.0, 0.0));
-    expect(value, isTrue);
-    await tester.pump();
-    await tester.drag(find.byType(CupertinoSwitch), const Offset(-30.0, 0.0));
-    expect(value, isFalse);
-
-    await tester.pumpWidget(
-      Directionality(
-        textDirection: TextDirection.ltr,
-        child: StatefulBuilder(
-          builder: (BuildContext context, StateSetter setState) {
-            return Center(
-              child: CupertinoSwitch(
-                value: value,
-                dragStartBehavior: DragStartBehavior.start,
-                onChanged: (bool newValue) {
-                  setState(() {
-                    value = newValue;
-                  });
-                },
-              ),
-            );
-          },
-        ),
-      ),
-    );
-    await tester.pumpAndSettle();
-    final Rect switchRect = tester.getRect(find.byType(CupertinoSwitch));
-
-    TestGesture gesture = await tester.startGesture(switchRect.center);
-    // We have to execute the drag in two frames because the first update will
-    // just set the start position.
-    await gesture.moveBy(const Offset(20.0, 0.0));
-    await gesture.moveBy(const Offset(20.0, 0.0));
-    expect(value, isTrue);
-    await gesture.up();
-    await tester.pump();
-
-    gesture = await tester.startGesture(switchRect.center);
-    await gesture.moveBy(const Offset(20.0, 0.0));
-    await gesture.moveBy(const Offset(20.0, 0.0));
-    expect(value, isTrue);
-    await gesture.up();
-    await tester.pump();
-
-    gesture = await tester.startGesture(switchRect.center);
-    await gesture.moveBy(const Offset(-20.0, 0.0));
-    await gesture.moveBy(const Offset(-20.0, 0.0));
-    expect(value, isFalse);
-  });
-
   testWidgets('Switch can drag (RTL)', (WidgetTester tester) async {
     bool value = false;
 
@@ -175,7 +90,6 @@
             return Center(
               child: CupertinoSwitch(
                 value: value,
-                dragStartBehavior: DragStartBehavior.down,
                 onChanged: (bool newValue) {
                   setState(() {
                     value = newValue;

diff --git a/packages/flutter/test/gestures/drag_test.dart b/packages/flutter/test/gestures/drag_test.dart
index 8349c0b..4d99466 100644
--- a/packages/flutter/test/gestures/drag_test.dart
+++ b/packages/flutter/test/gestures/drag_test.dart

@@ -58,7 +58,8 @@
     tester.route(pointer.move(const Offset(20.0, 30.0))); // moved 10 horizontally and 20 vertically which is 22 total
     expect(didStartPan, isTrue); // 22 > 18
     didStartPan = false;
-    expect(updatedScrollDelta, null);
+    expect(updatedScrollDelta, const Offset(10.0, 20.0));
+    updatedScrollDelta = null;
     expect(didEndPan, isFalse);
     expect(didTap, isFalse);
 
@@ -81,7 +82,7 @@
   });
 
   testGesture('Should recognize drag', (GestureTester tester) {
-    final HorizontalDragGestureRecognizer drag = HorizontalDragGestureRecognizer() ..dragStartBehavior = DragStartBehavior.down;
+    final HorizontalDragGestureRecognizer drag = HorizontalDragGestureRecognizer();
 
     bool didStartDrag = false;
     drag.onStart = (_) {
@@ -134,7 +135,7 @@
   });
 
   testGesture('Should report original timestamps', (GestureTester tester) {
-    final HorizontalDragGestureRecognizer drag = HorizontalDragGestureRecognizer() ..dragStartBehavior = DragStartBehavior.down;
+    final HorizontalDragGestureRecognizer drag = HorizontalDragGestureRecognizer();
 
     Duration startTimestamp;
     drag.onStart = (DragStartDetails details) {
@@ -164,98 +165,9 @@
     drag.dispose();
   });
 
-  testGesture('Should report most recent point to onStart by default', (GestureTester tester) {
-    final HorizontalDragGestureRecognizer drag = HorizontalDragGestureRecognizer();
-    final VerticalDragGestureRecognizer competingDrag = VerticalDragGestureRecognizer();
-
-    Offset positionAtOnStart;
-    drag.onStart = (DragStartDetails details) {
-      positionAtOnStart = details.globalPosition;
-    };
-
-    final TestPointer pointer = TestPointer(5);
-    final PointerDownEvent down = pointer.down(const Offset(10.0, 10.0));
-    drag.addPointer(down);
-    competingDrag.addPointer(down);
-    tester.closeArena(5);
-    tester.route(down);
-
-    tester.route(pointer.move(const Offset(30.0, 0.0)));
-    drag.dispose();
-    competingDrag.dispose();
-
-    expect(positionAtOnStart, const Offset(30.0, 00.0));
-  });
-
-  testGesture('Should report most recent point to onStart with a start configuration', (GestureTester tester) {
-    final HorizontalDragGestureRecognizer drag =
-    HorizontalDragGestureRecognizer();
-    final VerticalDragGestureRecognizer competingDrag = VerticalDragGestureRecognizer();
-
-    Offset positionAtOnStart;
-    drag.onStart = (DragStartDetails details) {
-      positionAtOnStart = details.globalPosition;
-    };
-    Offset updateOffset;
-    drag.onUpdate = (DragUpdateDetails details) {
-      updateOffset = details.globalPosition;
-    };
-
-    final TestPointer pointer = TestPointer(5);
-    final PointerDownEvent down = pointer.down(const Offset(10.0, 10.0));
-    drag.addPointer(down);
-    competingDrag.addPointer(down);
-    tester.closeArena(5);
-    tester.route(down);
-
-    tester.route(pointer.move(const Offset(30.0, 0.0)));
-    drag.dispose();
-    competingDrag.dispose();
-
-    expect(positionAtOnStart, const Offset(30.0, 0.0));
-    expect(updateOffset, null);
-  });
-
-  testGesture('Should report initial down point to onStart with a down configuration', (GestureTester tester) {
-    final HorizontalDragGestureRecognizer drag =
-    HorizontalDragGestureRecognizer() ..dragStartBehavior = DragStartBehavior.down;
-    final VerticalDragGestureRecognizer competingDrag = VerticalDragGestureRecognizer() ..dragStartBehavior = DragStartBehavior.down;
-
-    Offset positionAtOnStart;
-    drag.onStart = (DragStartDetails details) {
-      positionAtOnStart = details.globalPosition;
-    };
-    Offset updateOffset;
-    Offset updateDelta;
-    drag.onUpdate = (DragUpdateDetails details) {
-      updateOffset = details.globalPosition;
-      updateDelta = details.delta;
-    };
-
-    final TestPointer pointer = TestPointer(5);
-    final PointerDownEvent down = pointer.down(const Offset(10.0, 10.0));
-    drag.addPointer(down);
-    competingDrag.addPointer(down);
-    tester.closeArena(5);
-    tester.route(down);
-
-    tester.route(pointer.move(const Offset(30.0, 0.0)));
-    drag.dispose();
-    competingDrag.dispose();
-
-    expect(positionAtOnStart, const Offset(10.0, 10.0));
-
-    // The drag is horizontal so we're going to ignore the vertical delta position
-    // when calculating the new global position.
-    expect(updateOffset, const Offset(30.0, 10.0));
-    expect(updateDelta, const Offset(20.0, 0.0));
-  });
-
-  testGesture('Drag with multiple pointers in down behavior', (GestureTester tester) {
-    final HorizontalDragGestureRecognizer drag1 =
-    HorizontalDragGestureRecognizer() ..dragStartBehavior = DragStartBehavior.down;
-    final VerticalDragGestureRecognizer drag2 =
-    VerticalDragGestureRecognizer() ..dragStartBehavior = DragStartBehavior.down;
+  testGesture('Drag with multiple pointers', (GestureTester tester) {
+    final HorizontalDragGestureRecognizer drag1 = HorizontalDragGestureRecognizer();
+    final VerticalDragGestureRecognizer drag2 = VerticalDragGestureRecognizer();
 
     final List<String> log = <String>[];
     drag1.onDown = (_) { log.add('drag1-down'); };
@@ -323,7 +235,7 @@
   });
 
   testGesture('Clamp max velocity', (GestureTester tester) {
-    final HorizontalDragGestureRecognizer drag = HorizontalDragGestureRecognizer() ..dragStartBehavior = DragStartBehavior.down;
+    final HorizontalDragGestureRecognizer drag = HorizontalDragGestureRecognizer();
 
     Velocity velocity;
     double primaryVelocity;
@@ -357,7 +269,7 @@
   });
 
   testGesture('Synthesized pointer events are ignored for velocity tracking', (GestureTester tester) {
-    final HorizontalDragGestureRecognizer drag = HorizontalDragGestureRecognizer() ..dragStartBehavior = DragStartBehavior.down;
+    final HorizontalDragGestureRecognizer drag = HorizontalDragGestureRecognizer();
 
     Velocity velocity;
     drag.onEnd = (DragEndDetails details) {
@@ -391,7 +303,7 @@
   /// Checks that quick flick gestures with 1 down, 2 move and 1 up pointer
   /// events still have a velocity
   testGesture('Quick flicks have velocity', (GestureTester tester) {
-    final HorizontalDragGestureRecognizer drag = HorizontalDragGestureRecognizer() ..dragStartBehavior = DragStartBehavior.down;
+    final HorizontalDragGestureRecognizer drag = HorizontalDragGestureRecognizer();
 
     Velocity velocity;
     drag.onEnd = (DragEndDetails details) {
@@ -421,18 +333,16 @@
   });
 
   testGesture('Should recognize drag', (GestureTester tester) {
-    final HorizontalDragGestureRecognizer drag = HorizontalDragGestureRecognizer() ..dragStartBehavior = DragStartBehavior.down;
+    final HorizontalDragGestureRecognizer drag = HorizontalDragGestureRecognizer();
 
     bool didStartDrag = false;
     drag.onStart = (_) {
       didStartDrag = true;
     };
 
-    Offset updateDelta;
-    double updatePrimaryDelta;
+    double updatedDelta;
     drag.onUpdate = (DragUpdateDetails details) {
-      updateDelta = details.delta;
-      updatePrimaryDelta = details.primaryDelta;
+      updatedDelta = details.primaryDelta;
     };
 
     bool didEndDrag = false;
@@ -444,39 +354,31 @@
     final PointerDownEvent down = pointer.down(const Offset(10.0, 10.0));
     drag.addPointer(down);
     tester.closeArena(5);
-
     expect(didStartDrag, isFalse);
-    expect(updateDelta, isNull);
-    expect(updatePrimaryDelta, isNull);
+    expect(updatedDelta, isNull);
     expect(didEndDrag, isFalse);
 
     tester.route(down);
     expect(didStartDrag, isTrue);
-    expect(updateDelta, isNull);
-    expect(updatePrimaryDelta, isNull);
+    expect(updatedDelta, isNull);
     expect(didEndDrag, isFalse);
+
+    tester.route(pointer.move(const Offset(20.0, 25.0)));
+    expect(didStartDrag, isTrue);
     didStartDrag = false;
+    expect(updatedDelta, 10.0);
+    updatedDelta = null;
+    expect(didEndDrag, isFalse);
 
     tester.route(pointer.move(const Offset(20.0, 25.0)));
     expect(didStartDrag, isFalse);
-    expect(updateDelta, const Offset(10.0, 0.0));
-    expect(updatePrimaryDelta, 10.0);
+    expect(updatedDelta, 0.0);
+    updatedDelta = null;
     expect(didEndDrag, isFalse);
-    updateDelta = null;
-    updatePrimaryDelta = null;
-
-    tester.route(pointer.move(const Offset(20.0, 25.0)));
-    expect(didStartDrag, isFalse);
-    expect(updateDelta, const Offset(0.0, 0.0));
-    expect(updatePrimaryDelta, 0.0);
-    expect(didEndDrag, isFalse);
-    updateDelta = null;
-    updatePrimaryDelta = null;
 
     tester.route(pointer.up());
     expect(didStartDrag, isFalse);
-    expect(updateDelta, isNull);
-    expect(updatePrimaryDelta, isNull);
+    expect(updatedDelta, isNull);
     expect(didEndDrag, isTrue);
     didEndDrag = false;
 
@@ -484,36 +386,21 @@
   });
 
   testGesture('Should recognize drag', (GestureTester tester) {
-    final HorizontalDragGestureRecognizer drag = HorizontalDragGestureRecognizer() ..dragStartBehavior = DragStartBehavior.down;
+    final HorizontalDragGestureRecognizer drag = HorizontalDragGestureRecognizer();
 
-    Offset latestGlobalPosition;
-    drag.onStart = (DragStartDetails details) {
-      latestGlobalPosition = details.globalPosition;
-    };
-    Offset latestDelta;
+    Offset newGlobalPosition;
     drag.onUpdate = (DragUpdateDetails details) {
-      latestGlobalPosition = details.globalPosition;
-      latestDelta = details.delta;
+      newGlobalPosition = details.globalPosition;
     };
 
     final TestPointer pointer = TestPointer(5);
     final PointerDownEvent down = pointer.down(const Offset(10.0, 10.0));
     drag.addPointer(down);
-    tester.closeArena(5);
-
-    tester.route(down);
-    expect(latestGlobalPosition, const Offset(10.0, 10.0));
-    expect(latestDelta, isNull);
-
     tester.route(pointer.move(const Offset(20.0, 25.0)));
-    expect(latestGlobalPosition, const Offset(20.0, 25.0));
-    expect(latestDelta, const Offset(10.0, 0.0));
-
-    tester.route(pointer.move(const Offset(0.0, 45.0)));
-    expect(latestGlobalPosition, const Offset(0.0, 45.0));
-    expect(latestDelta, const Offset(-20.0, 0.0));
-
+    tester.closeArena(5);
+    tester.route(down);
+    expect(newGlobalPosition, const Offset(20.0, 10.0));
     tester.route(pointer.up());
     drag.dispose();
   });
-}
\ No newline at end of file
+}

diff --git a/packages/flutter/test/material/date_picker_test.dart b/packages/flutter/test/material/date_picker_test.dart
index a5fa105..ca5f19b 100644
--- a/packages/flutter/test/material/date_picker_test.dart
+++ b/packages/flutter/test/material/date_picker_test.dart

@@ -8,7 +8,6 @@
 import 'package:flutter/material.dart';
 import 'package:flutter/widgets.dart';
 import 'package:flutter_test/flutter_test.dart';
-import 'package:flutter/gestures.dart' show DragStartBehavior;
 
 import '../widgets/semantics_tester.dart';
 import 'feedback_tester.dart';
@@ -47,10 +46,8 @@
             return Container(
               width: 400.0,
               child: SingleChildScrollView(
-                dragStartBehavior: DragStartBehavior.down,
                 child: Material(
                   child: MonthPicker(
-                    dragStartBehavior: DragStartBehavior.down,
                     firstDate: DateTime(0),
                     lastDate: DateTime(9999),
                     key: _datePickerKey,
@@ -66,7 +63,7 @@
             );
           },
         ),
-      ),
+      )
     );
 
     expect(_selectedDate, equals(DateTime(2016, DateTime.july, 26)));

diff --git a/packages/flutter/test/material/ink_well_test.dart b/packages/flutter/test/material/ink_well_test.dart
index e89d1ba..0ae9410 100644
--- a/packages/flutter/test/material/ink_well_test.dart
+++ b/packages/flutter/test/material/ink_well_test.dart

@@ -5,7 +5,6 @@
 import 'package:flutter/material.dart';
 import 'package:flutter/rendering.dart';
 import 'package:flutter_test/flutter_test.dart';
-import 'package:flutter/gestures.dart';
 
 import '../rendering/mock_canvas.dart';
 import '../widgets/semantics_tester.dart';
@@ -165,7 +164,6 @@
               link: LayerLink(),
               child: ListView(
                 addAutomaticKeepAlives: keepAlive,
-                dragStartBehavior: DragStartBehavior.down,
                 children: <Widget>[
                   Container(height: 500.0, child: InkWell(onTap: () { }, child: const Placeholder())),
                   Container(height: 500.0),

diff --git a/packages/flutter/test/material/paginated_data_table_test.dart b/packages/flutter/test/material/paginated_data_table_test.dart
index c1d833e..9221a6b 100644
--- a/packages/flutter/test/material/paginated_data_table_test.dart
+++ b/packages/flutter/test/material/paginated_data_table_test.dart

@@ -4,7 +4,6 @@
 
 import 'package:flutter/material.dart';
 import 'package:flutter_test/flutter_test.dart';
-import 'package:flutter/gestures.dart' show DragStartBehavior;
 
 import 'data_table_test_utils.dart';
 
@@ -249,29 +248,26 @@
 
   testWidgets('PaginatedDataTable footer scrolls', (WidgetTester tester) async {
     final TestDataSource source = TestDataSource();
-    await tester.pumpWidget(
-      MaterialApp(
-        home: Align(
-          alignment: Alignment.topLeft,
-          child: SizedBox(
-            width: 100.0,
-            child: PaginatedDataTable(
-              header: const Text('HEADER'),
-              source: source,
-              rowsPerPage: 5,
-              dragStartBehavior: DragStartBehavior.down,
-              availableRowsPerPage: const <int>[ 5 ],
-              onRowsPerPageChanged: (int rowsPerPage) { },
-              columns: const <DataColumn>[
-                DataColumn(label: Text('COL1')),
-                DataColumn(label: Text('COL2')),
-                DataColumn(label: Text('COL3')),
-              ],
-            ),
+    await tester.pumpWidget(MaterialApp(
+      home: Align(
+        alignment: Alignment.topLeft,
+        child: SizedBox(
+          width: 100.0,
+          child: PaginatedDataTable(
+            header: const Text('HEADER'),
+            source: source,
+            rowsPerPage: 5,
+            availableRowsPerPage: const <int>[ 5 ],
+            onRowsPerPageChanged: (int rowsPerPage) { },
+            columns: const <DataColumn>[
+              DataColumn(label: Text('COL1')),
+              DataColumn(label: Text('COL2')),
+              DataColumn(label: Text('COL3')),
+            ],
           ),
         ),
       ),
-    );
+    ));
     expect(find.text('Rows per page:'), findsOneWidget);
     expect(tester.getTopLeft(find.text('Rows per page:')).dx, lessThan(0.0)); // off screen
     await tester.dragFrom(

diff --git a/packages/flutter/test/material/scaffold_test.dart b/packages/flutter/test/material/scaffold_test.dart
index d104601..f8d87d3 100644
--- a/packages/flutter/test/material/scaffold_test.dart
+++ b/packages/flutter/test/material/scaffold_test.dart

@@ -6,7 +6,6 @@
 import 'package:flutter/material.dart';
 import 'package:flutter/rendering.dart';
 import 'package:flutter_test/flutter_test.dart';
-import 'package:flutter/gestures.dart' show DragStartBehavior;
 
 import '../widgets/semantics_tester.dart';
 
@@ -202,7 +201,6 @@
           drawer: Drawer(
             key: drawerKey,
             child: ListView(
-              dragStartBehavior: DragStartBehavior.down,
               controller: scrollOffset,
               children: List<Widget>.generate(10,
                 (int index) => SizedBox(height: 100.0, child: Text('D$index'))
@@ -632,7 +630,6 @@
               viewInsets: EdgeInsets.only(bottom: 200.0),
             ),
             child: Scaffold(
-              drawerDragStartBehavior: DragStartBehavior.down,
               appBar: PreferredSize(
                 preferredSize: const Size(11.0, 13.0),
                 child: Container(

diff --git a/packages/flutter/test/material/switch_test.dart b/packages/flutter/test/material/switch_test.dart
index 84b8beb..59a7c5f 100644
--- a/packages/flutter/test/material/switch_test.dart
+++ b/packages/flutter/test/material/switch_test.dart

@@ -2,12 +2,12 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+
 import 'package:flutter/cupertino.dart';
 import 'package:flutter/material.dart';
 import 'package:flutter/rendering.dart';
 import 'package:flutter/services.dart';
 import 'package:flutter_test/flutter_test.dart';
-import 'package:flutter/gestures.dart';
 
 import '../rendering/mock_canvas.dart';
 import '../widgets/semantics_tester.dart';
@@ -25,7 +25,6 @@
             return Material(
               child: Center(
                 child: Switch(
-                  dragStartBehavior: DragStartBehavior.down,
                   key: switchKey,
                   value: value,
                   onChanged: (bool newValue) {
@@ -55,7 +54,6 @@
           child: Material(
             child: Center(
               child: Switch(
-                dragStartBehavior: DragStartBehavior.down,
                 value: true,
                 onChanged: (bool newValue) {},
               ),
@@ -75,7 +73,6 @@
           child: Material(
             child: Center(
               child: Switch(
-                dragStartBehavior: DragStartBehavior.down,
                 value: true,
                 onChanged: (bool newValue) {},
               ),
@@ -99,7 +96,6 @@
             return Material(
               child: Center(
                 child: Switch(
-                  dragStartBehavior: DragStartBehavior.down,
                   value: value,
                   onChanged: (bool newValue) {
                     setState(() {
@@ -135,93 +131,6 @@
     expect(value, isFalse);
   });
 
-  testWidgets('Switch can drag with dragStartBehavior', (WidgetTester tester) async {
-    bool value = false;
-
-    await tester.pumpWidget(
-      Directionality(
-        textDirection: TextDirection.ltr,
-        child: StatefulBuilder(
-          builder: (BuildContext context, StateSetter setState) {
-            return Material(
-              child: Center(
-                child: Switch(
-                    dragStartBehavior: DragStartBehavior.down,
-                    value: value,
-                    onChanged: (bool newValue) {
-                      setState(() {
-                        value = newValue;
-                      }
-                    );
-                  }
-                ),
-              ),
-            );
-          },
-        ),
-      ),
-    );
-
-    expect(value, isFalse);
-    await tester.drag(find.byType(Switch), const Offset(-30.0, 0.0));
-    expect(value, isFalse);
-
-    await tester.drag(find.byType(Switch), const Offset(30.0, 0.0));
-    expect(value, isTrue);
-    await tester.pump();
-    await tester.drag(find.byType(Switch), const Offset(30.0, 0.0));
-    expect(value, isTrue);
-    await tester.pump();
-    await tester.drag(find.byType(Switch), const Offset(-30.0, 0.0));
-    expect(value, isFalse);
-
-    await tester.pumpWidget(
-      Directionality(
-        textDirection: TextDirection.ltr,
-        child: StatefulBuilder(
-          builder: (BuildContext context, StateSetter setState) {
-            return Material(
-              child: Center(
-                child: Switch(
-                    dragStartBehavior: DragStartBehavior.start,
-                    value: value,
-                    onChanged: (bool newValue) {
-                      setState(() {
-                        value = newValue;
-                      });
-                    }
-                ),
-              ),
-            );
-          },
-        ),
-      ),
-    );
-    await tester.pumpAndSettle();
-    final Rect switchRect = tester.getRect(find.byType(Switch));
-
-    TestGesture gesture = await tester.startGesture(switchRect.center);
-    // We have to execute the drag in two frames because the first update will
-    // just set the start position.
-    await gesture.moveBy(const Offset(20.0, 0.0));
-    await gesture.moveBy(const Offset(20.0, 0.0));
-    expect(value, isTrue);
-    await gesture.up();
-    await tester.pump();
-
-    gesture = await tester.startGesture(switchRect.center);
-    await gesture.moveBy(const Offset(20.0, 0.0));
-    await gesture.moveBy(const Offset(20.0, 0.0));
-    expect(value, isTrue);
-    await gesture.up();
-    await tester.pump();
-
-    gesture = await tester.startGesture(switchRect.center);
-    await gesture.moveBy(const Offset(-20.0, 0.0));
-    await gesture.moveBy(const Offset(-20.0, 0.0));
-    expect(value, isFalse);
-  });
-
   testWidgets('Switch can drag (RTL)', (WidgetTester tester) async {
     bool value = false;
 
@@ -233,7 +142,6 @@
             return Material(
               child: Center(
                 child: Switch(
-                  dragStartBehavior: DragStartBehavior.down,
                   value: value,
                   onChanged: (bool newValue) {
                     setState(() {
@@ -277,7 +185,6 @@
             return Material(
               child: Center(
                 child: Switch(
-                  dragStartBehavior: DragStartBehavior.down,
                   value: value,
                   onChanged: (bool newValue) {
                     setState(() {
@@ -399,7 +306,6 @@
             return Material(
               child: Center(
                 child: Switch(
-                  dragStartBehavior: DragStartBehavior.down,
                   value: value,
                   onChanged: (bool newValue) {
                     setState(() {
@@ -459,7 +365,6 @@
             return Material(
               child: Center(
                 child: Switch(
-                  dragStartBehavior: DragStartBehavior.down,
                   value: value,
                   onChanged: (bool newValue) {
                     setState(() {

diff --git a/packages/flutter/test/material/text_field_test.dart b/packages/flutter/test/material/text_field_test.dart
index 59b90ca..3e1327b 100644
--- a/packages/flutter/test/material/text_field_test.dart
+++ b/packages/flutter/test/material/text_field_test.dart

@@ -12,7 +12,6 @@
 import 'package:flutter_test/flutter_test.dart';
 import 'package:flutter/rendering.dart';
 import 'package:flutter/services.dart';
-import 'package:flutter/gestures.dart' show DragStartBehavior;
 
 import '../widgets/semantics_tester.dart';
 import 'feedback_tester.dart';
@@ -502,12 +501,9 @@
     final TextEditingController controller = TextEditingController();
 
     await tester.pumpWidget(
-      MaterialApp(
-        home: Material(
-          child: TextField(
-            dragStartBehavior: DragStartBehavior.down,
-            controller: controller,
-          ),
+      overlay(
+        child: TextField(
+          controller: controller,
         ),
       ),
     );
@@ -546,7 +542,7 @@
     await tester.pump();
 
     expect(controller.selection.baseOffset, selection.baseOffset);
-    expect(controller.selection.extentOffset, selection.extentOffset);
+    expect(controller.selection.extentOffset, selection.extentOffset+2);
 
     // Drag the left handle 2 letters to the left.
     handlePos = endpoints[0].point + const Offset(-1.0, 1.0);
@@ -558,8 +554,8 @@
     await gesture.up();
     await tester.pump();
 
-    expect(controller.selection.baseOffset, selection.baseOffset);
-    expect(controller.selection.extentOffset, selection.extentOffset);
+    expect(controller.selection.baseOffset, selection.baseOffset-2);
+    expect(controller.selection.extentOffset, selection.extentOffset+2);
   });
 
   testWidgets('Can use selection toolbar', (WidgetTester tester) async {
@@ -830,7 +826,6 @@
     await tester.pumpWidget(
       overlay(
         child: TextField(
-          dragStartBehavior: DragStartBehavior.down,
           controller: controller,
           style: const TextStyle(color: Colors.black, fontSize: 34.0),
           maxLines: 3,
@@ -914,7 +909,6 @@
     await tester.pumpWidget(
       overlay(
         child: TextField(
-          dragStartBehavior: DragStartBehavior.down,
           key: textFieldKey,
           controller: controller,
           style: const TextStyle(color: Colors.black, fontSize: 34.0),

diff --git a/packages/flutter/test/widgets/automatic_keep_alive_test.dart b/packages/flutter/test/widgets/automatic_keep_alive_test.dart
index 68bfe86..404e633 100644
--- a/packages/flutter/test/widgets/automatic_keep_alive_test.dart
+++ b/packages/flutter/test/widgets/automatic_keep_alive_test.dart

@@ -5,7 +5,6 @@
 import 'package:flutter/rendering.dart';
 import 'package:flutter/widgets.dart';
 import 'package:flutter_test/flutter_test.dart';
-import 'package:flutter/gestures.dart' show DragStartBehavior;
 
 class Leaf extends StatefulWidget {
   const Leaf({ Key key, this.child }) : super(key: key);
@@ -477,7 +476,6 @@
     await tester.pumpWidget(Directionality(
       textDirection: TextDirection.ltr,
       child: ListView.builder(
-        dragStartBehavior: DragStartBehavior.down,
         addSemanticIndexes: false,
         itemCount: 50,
         itemBuilder: (BuildContext context, int index){

diff --git a/packages/flutter/test/widgets/dismissible_test.dart b/packages/flutter/test/widgets/dismissible_test.dart
index 9623121..420fdcc 100644
--- a/packages/flutter/test/widgets/dismissible_test.dart
+++ b/packages/flutter/test/widgets/dismissible_test.dart

@@ -5,7 +5,6 @@
 import 'package:flutter/rendering.dart';
 import 'package:flutter/widgets.dart';
 import 'package:flutter_test/flutter_test.dart';
-import 'package:flutter/gestures.dart' show DragStartBehavior;
 
 const double itemExtent = 100.0;
 Axis scrollDirection = Axis.vertical;
@@ -22,7 +21,6 @@
       builder: (BuildContext context, StateSetter setState) {
         Widget buildDismissibleItem(int item) {
           return Dismissible(
-            dragStartBehavior: DragStartBehavior.down,
             key: ValueKey<int>(item),
             direction: dismissDirection,
             onDismissed: (DismissDirection direction) {
@@ -51,7 +49,6 @@
         return Container(
           padding: const EdgeInsets.all(10.0),
           child: ListView(
-            dragStartBehavior: DragStartBehavior.down,
             scrollDirection: scrollDirection,
             itemExtent: itemExtent,
             children: <int>[0, 1, 2, 3, 4]
@@ -202,7 +199,6 @@
   @override
   Widget build(BuildContext context) {
     return Dismissible(
-      dragStartBehavior: DragStartBehavior.down,
       key: ObjectKey(text),
       child: AspectRatio(
         aspectRatio: 1.0,

diff --git a/packages/flutter/test/widgets/draggable_test.dart b/packages/flutter/test/widgets/draggable_test.dart
index ef8e964..97941fc 100644
--- a/packages/flutter/test/widgets/draggable_test.dart
+++ b/packages/flutter/test/widgets/draggable_test.dart

@@ -383,7 +383,6 @@
 
     await tester.pumpWidget(MaterialApp(
       home: ListView(
-        dragStartBehavior: DragStartBehavior.down,
         children: <Widget>[
           DragTarget<int>(
             builder: (BuildContext context, List<int> data, List<dynamic> rejects) {
@@ -490,7 +489,6 @@
 
     await tester.pumpWidget(MaterialApp(
       home: ListView(
-        dragStartBehavior: DragStartBehavior.down,
         scrollDirection: Axis.horizontal,
         children: <Widget>[
           DragTarget<int>(

diff --git a/packages/flutter/test/widgets/drawer_test.dart b/packages/flutter/test/widgets/drawer_test.dart
index 5dc9a7f..30868b0 100644
--- a/packages/flutter/test/widgets/drawer_test.dart
+++ b/packages/flutter/test/widgets/drawer_test.dart

@@ -9,7 +9,6 @@
 import 'package:flutter/material.dart';
 import 'package:flutter/rendering.dart';
 import 'package:flutter/widgets.dart';
-import 'package:flutter/gestures.dart' show DragStartBehavior;
 
 import 'semantics_tester.dart';
 
@@ -83,7 +82,6 @@
     await tester.pumpWidget(
       MaterialApp(
         home: Scaffold(
-          drawerDragStartBehavior: DragStartBehavior.down,
           key: scaffoldKey,
           drawer: Drawer(
             child: ListView(
@@ -136,7 +134,6 @@
         home: Directionality(
           textDirection: TextDirection.rtl,
           child: Scaffold(
-            drawerDragStartBehavior: DragStartBehavior.down,
             key: scaffoldKey,
             drawer: Drawer(
               child: ListView(

diff --git a/packages/flutter/test/widgets/gesture_detector_test.dart b/packages/flutter/test/widgets/gesture_detector_test.dart
index 922126b..f7acb45 100644
--- a/packages/flutter/test/widgets/gesture_detector_test.dart
+++ b/packages/flutter/test/widgets/gesture_detector_test.dart

@@ -64,7 +64,6 @@
     const Offset upLocation = Offset(10.0, 50.0); // must be far enough to be more than kTouchSlop
 
     final Widget widget = GestureDetector(
-      dragStartBehavior: DragStartBehavior.down,
       onVerticalDragUpdate: (DragUpdateDetails details) { dragDistance += details.primaryDelta; },
       onVerticalDragEnd: (DragEndDetails details) { gestureCount += 1; },
       onHorizontalDragUpdate: (DragUpdateDetails details) { fail('gesture should not match'); },

diff --git a/packages/flutter/test/widgets/grid_view_test.dart b/packages/flutter/test/widgets/grid_view_test.dart
index 3938ac1..38b4786 100644
--- a/packages/flutter/test/widgets/grid_view_test.dart
+++ b/packages/flutter/test/widgets/grid_view_test.dart

@@ -4,7 +4,6 @@
 
 import 'package:flutter_test/flutter_test.dart';
 import 'package:flutter/widgets.dart';
-import 'package:flutter/gestures.dart' show DragStartBehavior;
 
 import '../rendering/mock_canvas.dart';
 import 'states.dart';
@@ -15,7 +14,6 @@
       Directionality(
         textDirection: TextDirection.ltr,
         child: GridView.count(
-          dragStartBehavior: DragStartBehavior.down,
           crossAxisCount: 4,
           children: const <Widget>[],
         ),
@@ -30,11 +28,9 @@
       Directionality(
         textDirection: TextDirection.ltr,
         child: GridView.count(
-          dragStartBehavior: DragStartBehavior.down,
           crossAxisCount: 4,
           children: kStates.map<Widget>((String state) {
             return GestureDetector(
-              dragStartBehavior: DragStartBehavior.down,
               onTap: () {
                 log.add(state);
               },
@@ -103,11 +99,9 @@
       Directionality(
         textDirection: TextDirection.ltr,
         child: GridView.extent(
-          dragStartBehavior: DragStartBehavior.down,
           maxCrossAxisExtent: 200.0,
           children: kStates.map<Widget>((String state) {
             return GestureDetector(
-              dragStartBehavior: DragStartBehavior.down,
               onTap: () {
                 log.add(state);
               },

diff --git a/packages/flutter/test/widgets/heroes_test.dart b/packages/flutter/test/widgets/heroes_test.dart
index 23e6460..e33291b 100644
--- a/packages/flutter/test/widgets/heroes_test.dart
+++ b/packages/flutter/test/widgets/heroes_test.dart

@@ -1373,11 +1373,8 @@
     expect(find.byKey(secondKey), isOnstage);
     expect(find.byKey(secondKey), isInCard);
 
-    final TestGesture  gesture = await tester.startGesture(const Offset(5.0, 200.0));
-    await gesture.moveBy(const Offset(20.0, 0.0));
-    await gesture.moveBy(const Offset(180.0, 0.0));
-    await gesture.up();
-    await tester.pump();
+    final TestGesture gesture = await tester.startGesture(const Offset(5.0, 200.0));
+    await gesture.moveBy(const Offset(200.0, 0.0));
 
     await tester.pump();
 

diff --git a/packages/flutter/test/widgets/listview_end_append_test.dart b/packages/flutter/test/widgets/listview_end_append_test.dart
index e09969e..0f9f1f4 100644
--- a/packages/flutter/test/widgets/listview_end_append_test.dart
+++ b/packages/flutter/test/widgets/listview_end_append_test.dart

@@ -4,7 +4,6 @@
 
 import 'package:flutter_test/flutter_test.dart';
 import 'package:flutter/widgets.dart';
-import 'package:flutter/gestures.dart' show DragStartBehavior;
 
 void main() {
   testWidgets('ListView.builder() fixed itemExtent, scroll to end, append, scroll', (WidgetTester tester) async {
@@ -14,7 +13,6 @@
       return Directionality(
         textDirection: TextDirection.ltr,
         child: ListView.builder(
-          dragStartBehavior: DragStartBehavior.down,
           itemExtent: 200.0,
           itemCount: itemCount,
           itemBuilder: (BuildContext context, int index) => Text('item $index'),
@@ -42,7 +40,6 @@
       return Directionality(
         textDirection: TextDirection.ltr,
         child: ListView.builder(
-          dragStartBehavior: DragStartBehavior.down,
           itemCount: itemCount,
           itemBuilder: (BuildContext context, int index) {
             return SizedBox(

diff --git a/packages/flutter/test/widgets/nested_scroll_view_test.dart b/packages/flutter/test/widgets/nested_scroll_view_test.dart
index 354126d..b52360b 100644
--- a/packages/flutter/test/widgets/nested_scroll_view_test.dart
+++ b/packages/flutter/test/widgets/nested_scroll_view_test.dart

@@ -5,7 +5,6 @@
 import 'package:flutter/foundation.dart';
 import 'package:flutter/material.dart';
 import 'package:flutter_test/flutter_test.dart';
-import 'package:flutter/gestures.dart' show DragStartBehavior;
 
 import '../rendering/mock_canvas.dart';
 
@@ -35,11 +34,9 @@
       child: MediaQuery(
         data: const MediaQueryData(),
         child: Scaffold(
-          drawerDragStartBehavior: DragStartBehavior.down,
           body: DefaultTabController(
             length: 4,
             child: NestedScrollView(
-              dragStartBehavior: DragStartBehavior.down,
               controller: controller,
               headerSliverBuilder: (BuildContext context, bool innerBoxIsScrolled) {
                 return <Widget>[
@@ -82,7 +79,6 @@
                     ],
                   ),
                   ListView(
-                    dragStartBehavior: DragStartBehavior.down,
                     children: <Widget>[
                       Container(
                         height: 100.0,
@@ -94,7 +90,6 @@
                     child: const Center(child: Text('ccc1')),
                   ),
                   ListView(
-                    dragStartBehavior: DragStartBehavior.down,
                     children: <Widget>[
                       Container(
                         height: 10000.0,
@@ -366,7 +361,6 @@
         DefaultTabController(
           length: _tabs.length, // This is the number of tabs.
           child: NestedScrollView(
-            dragStartBehavior: DragStartBehavior.down,
             headerSliverBuilder: (BuildContext context, bool innerBoxIsScrolled) {
               buildCount += 1; // THIS LINE IS NOT IN THE ORIGINAL -- ADDED FOR TEST
               // These are the slivers that show up in the "outer" scroll view.
@@ -396,14 +390,12 @@
                     bottom: TabBar(
                       // These are the widgets to put in each tab in the tab bar.
                       tabs: _tabs.map<Widget>((String name) => Tab(text: name)).toList(),
-                      dragStartBehavior: DragStartBehavior.down,
                     ),
                   ),
                 ),
               ];
             },
             body: TabBarView(
-              dragStartBehavior: DragStartBehavior.down,
               // These are the contents of the tab views, below the tabs.
               children: _tabs.map<Widget>((String name) {
                 return SafeArea(
@@ -424,7 +416,6 @@
                         // it allows the list to remember its scroll position when
                         // the tab view is not on the screen.
                         key: PageStorageKey<String>(name),
-                        dragStartBehavior: DragStartBehavior.down,
                         slivers: <Widget>[
                           SliverOverlapInjector(
                             // This is the flip side of the SliverOverlapAbsorber above.
@@ -599,7 +590,6 @@
           child: DefaultTabController(
             length: 1,
             child: NestedScrollView(
-              dragStartBehavior: DragStartBehavior.down,
               headerSliverBuilder: (BuildContext context, bool innerBoxIsScrolled) {
                 return <Widget>[
                   const SliverPersistentHeader(
@@ -608,7 +598,6 @@
                 ];
               },
               body: SingleChildScrollView(
-                dragStartBehavior: DragStartBehavior.down,
                 child: Container(
                   height: 1000.0,
                   child: const Placeholder(key: key2),

diff --git a/packages/flutter/test/widgets/page_view_test.dart b/packages/flutter/test/widgets/page_view_test.dart
index 4c858ad..c8ecdbe 100644
--- a/packages/flutter/test/widgets/page_view_test.dart
+++ b/packages/flutter/test/widgets/page_view_test.dart

@@ -6,7 +6,6 @@
 import 'package:flutter/material.dart';
 import 'package:flutter/rendering.dart';
 import 'package:flutter/widgets.dart';
-import 'package:flutter/gestures.dart' show DragStartBehavior;
 
 import 'semantics_tester.dart';
 import 'states.dart';
@@ -20,10 +19,8 @@
     await tester.pumpWidget(Directionality(
       textDirection: TextDirection.ltr,
       child: PageView(
-        dragStartBehavior: DragStartBehavior.down,
         children: kStates.map<Widget>((String state) {
           return GestureDetector(
-            dragStartBehavior: DragStartBehavior.down,
             onTap: () {
               log.add(state);
             },

diff --git a/packages/flutter/test/widgets/scroll_notification_test.dart b/packages/flutter/test/widgets/scroll_notification_test.dart
index b4cdcec..0fbadfa 100644
--- a/packages/flutter/test/widgets/scroll_notification_test.dart
+++ b/packages/flutter/test/widgets/scroll_notification_test.dart

@@ -60,7 +60,6 @@
         return false;
       },
       child: SingleChildScrollView(
-        dragStartBehavior: DragStartBehavior.down,
         child: SizedBox(
           height: 1200.0,
           child: NotificationListener<ScrollNotification>(
@@ -71,14 +70,11 @@
             },
             child: Container(
               padding: const EdgeInsets.all(50.0),
-              child: const SingleChildScrollView(
-                child: SizedBox(height: 1200.0),
-                dragStartBehavior: DragStartBehavior.down,
-              ),
-            ),
-          ),
-        ),
-      ),
+              child: const SingleChildScrollView(child: SizedBox(height: 1200.0))
+            )
+          )
+        )
+      )
     ));
 
     final TestGesture gesture = await tester.startGesture(const Offset(100.0, 100.0));

diff --git a/packages/flutter/test/widgets/scroll_view_test.dart b/packages/flutter/test/widgets/scroll_view_test.dart
index 3fcd382..15e161d 100644
--- a/packages/flutter/test/widgets/scroll_view_test.dart
+++ b/packages/flutter/test/widgets/scroll_view_test.dart

@@ -4,7 +4,6 @@
 
 import 'package:flutter_test/flutter_test.dart';
 import 'package:flutter/widgets.dart';
-import 'package:flutter/gestures.dart' show DragStartBehavior;
 import 'package:flutter/material.dart';
 
 import 'states.dart';
@@ -17,7 +16,6 @@
       Directionality(
         textDirection: TextDirection.ltr,
         child: ListView(
-          dragStartBehavior: DragStartBehavior.down,
           children: kStates.map<Widget>((String state) {
             return GestureDetector(
               onTap: () {
@@ -28,7 +26,6 @@
                 color: const Color(0xFF0000FF),
                 child: Text(state),
               ),
-              dragStartBehavior: DragStartBehavior.down,
             );
           }).toList(),
         ),
@@ -57,7 +54,6 @@
       return Directionality(
         textDirection: TextDirection.ltr,
         child: ListView(
-          dragStartBehavior: DragStartBehavior.down,
           children: kStates.take(n).map<Widget>((String state) {
             return Container(
               height: 200.0,
@@ -89,13 +85,11 @@
       Directionality(
         textDirection: TextDirection.ltr,
         child: CustomScrollView(
-          dragStartBehavior: DragStartBehavior.down,
           slivers: <Widget>[
             SliverList(
               delegate: SliverChildListDelegate(
                 kStates.map<Widget>((String state) {
                   return GestureDetector(
-                    dragStartBehavior: DragStartBehavior.down,
                     onTap: () {
                       log.add(state);
                     },

diff --git a/packages/flutter/test/widgets/scrollable_fling_test.dart b/packages/flutter/test/widgets/scrollable_fling_test.dart
index 68b8ba6..2dd30a0 100644
--- a/packages/flutter/test/widgets/scrollable_fling_test.dart
+++ b/packages/flutter/test/widgets/scrollable_fling_test.dart

@@ -4,7 +4,6 @@
 
 import 'package:flutter_test/flutter_test.dart';
 import 'package:flutter/material.dart';
-import 'package:flutter/gestures.dart' show DragStartBehavior;
 
 const TextStyle testFont = TextStyle(
   color: Color(0xFF00FF00),
@@ -20,7 +19,6 @@
     home: Container(
       color: const Color(0xFF111111),
       child: ListView.builder(
-        dragStartBehavior: DragStartBehavior.down,
         itemBuilder: (BuildContext context, int index) {
           return Text('$index', style: testFont);
         },
@@ -66,7 +64,7 @@
     await tester.pumpWidget(
       Directionality(
         textDirection: TextDirection.ltr,
-        child: ListView(children: textWidgets, dragStartBehavior: DragStartBehavior.down)
+        child: ListView(children: textWidgets)
       ),
     );
 
@@ -94,7 +92,7 @@
     await tester.pumpWidget(
       Directionality(
         textDirection: TextDirection.ltr,
-        child: ListView(children: textWidgets, dragStartBehavior: DragStartBehavior.down)
+        child: ListView(children: textWidgets)
       ),
     );
 

diff --git a/packages/flutter/test/widgets/scrollable_list_hit_testing_test.dart b/packages/flutter/test/widgets/scrollable_list_hit_testing_test.dart
index 2f7f0bf..c06da6d 100644
--- a/packages/flutter/test/widgets/scrollable_list_hit_testing_test.dart
+++ b/packages/flutter/test/widgets/scrollable_list_hit_testing_test.dart

@@ -5,7 +5,6 @@
 import 'package:flutter_test/flutter_test.dart';
 import 'package:flutter/rendering.dart';
 import 'package:flutter/widgets.dart';
-import 'package:flutter/gestures.dart' show DragStartBehavior;
 
 const List<int> items = <int>[0, 1, 2, 3, 4, 5];
 
@@ -19,7 +18,6 @@
           child: Container(
             height: 50.0,
             child: ListView(
-              dragStartBehavior: DragStartBehavior.down,
               itemExtent: 290.0,
               scrollDirection: Axis.horizontal,
               children: items.map<Widget>((int item) {
@@ -27,7 +25,6 @@
                   child: GestureDetector(
                     onTap: () { tapped.add(item); },
                     child: Text('$item'),
-                    dragStartBehavior: DragStartBehavior.down,
                   ),
                 );
               }).toList(),
@@ -63,7 +60,6 @@
           child: Container(
             width: 50.0,
             child: ListView(
-              dragStartBehavior: DragStartBehavior.down,
               itemExtent: 290.0,
               scrollDirection: Axis.vertical,
               children: items.map<Widget>((int item) {
@@ -71,7 +67,6 @@
                   child: GestureDetector(
                     onTap: () { tapped.add(item); },
                     child: Text('$item'),
-                    dragStartBehavior: DragStartBehavior.down,
                   ),
                 );
               }).toList(),

diff --git a/packages/flutter/test/widgets/scrollable_semantics_test.dart b/packages/flutter/test/widgets/scrollable_semantics_test.dart
index 986eb6b..2dcf7e6 100644
--- a/packages/flutter/test/widgets/scrollable_semantics_test.dart
+++ b/packages/flutter/test/widgets/scrollable_semantics_test.dart

@@ -8,7 +8,6 @@
 import 'package:flutter_test/flutter_test.dart';
 import 'package:flutter/rendering.dart';
 import 'package:flutter/widgets.dart';
-import 'package:flutter/gestures.dart' show DragStartBehavior;
 
 import 'semantics_tester.dart';
 
@@ -267,7 +266,6 @@
     await tester.pumpWidget(Directionality(
       textDirection: TextDirection.ltr,
       child: ListView.builder(
-        dragStartBehavior: DragStartBehavior.down,
         itemExtent: 20.0,
         itemBuilder: (BuildContext context, int index) {
           return Text('entry $index');

diff --git a/packages/flutter/test/widgets/widget_inspector_test.dart b/packages/flutter/test/widgets/widget_inspector_test.dart
index bfefa12..8b77bb2 100644
--- a/packages/flutter/test/widgets/widget_inspector_test.dart
+++ b/packages/flutter/test/widgets/widget_inspector_test.dart

@@ -12,7 +12,6 @@
 import 'package:flutter/rendering.dart';
 import 'package:flutter/widgets.dart';
 import 'package:flutter_test/flutter_test.dart';
-import 'package:flutter/gestures.dart' show DragStartBehavior;
 
 // Start of block of code where widget creation location line numbers and
 // columns will impact whether tests pass.
@@ -397,7 +396,6 @@
             key: inspectorKey,
             selectButtonBuilder: selectButtonBuilder,
             child: ListView(
-              dragStartBehavior: DragStartBehavior.down,
               children: <Widget>[
                 Container(
                   key: childKey,
@@ -1511,7 +1509,7 @@
       _CreationLocation location = knownLocations[id];
       expect(location.file, equals(file));
       // ClockText widget.
-      expect(location.line, equals(50));
+      expect(location.line, equals(49));
       expect(location.column, equals(9));
       expect(count, equals(1));
 
@@ -1520,7 +1518,7 @@
       location = knownLocations[id];
       expect(location.file, equals(file));
       // Text widget in _ClockTextState build method.
-      expect(location.line, equals(88));
+      expect(location.line, equals(87));
       expect(location.column, equals(12));
       expect(count, equals(1));
 
@@ -1545,7 +1543,7 @@
       location = knownLocations[id];
       expect(location.file, equals(file));
       // ClockText widget.
-      expect(location.line, equals(50));
+      expect(location.line, equals(49));
       expect(location.column, equals(9));
       expect(count, equals(3)); // 3 clock widget instances rebuilt.
 
@@ -1554,7 +1552,7 @@
       location = knownLocations[id];
       expect(location.file, equals(file));
       // Text widget in _ClockTextState build method.
-      expect(location.line, equals(88));
+      expect(location.line, equals(87));
       expect(location.column, equals(12));
       expect(count, equals(3)); // 3 clock widget instances rebuilt.