diff --git a/dev/devicelab/manifest.yaml b/dev/devicelab/manifest.yaml
index bda1cdb..14cda25 100644
--- a/dev/devicelab/manifest.yaml
+++ b/dev/devicelab/manifest.yaml
@@ -645,14 +645,12 @@
       A smoke test that runs on macOS Catalina, which is a clone of the Gallery startup latency test.
     stage: devicelab_ios
     required_agent_capabilities: ["mac-catalina/ios"]
-    flaky: true
 
   smoke_catalina_hot_mode_dev_cycle_ios__benchmark:
     description: >
       A some test that runs on macOS Catalina, which is a clone of the Dart VM hot patching performance benchmarking.
     stage: devicelab_ios
     required_agent_capabilities: ["mac-catalina/ios"]
-    flaky: true
 
   smoke_catalina_start_up:
     description: >
diff --git a/dev/integration_tests/flutter_gallery/lib/gallery/updater.dart b/dev/integration_tests/flutter_gallery/lib/gallery/updater.dart
index ce15012..9a81ac7 100644
--- a/dev/integration_tests/flutter_gallery/lib/gallery/updater.dart
+++ b/dev/integration_tests/flutter_gallery/lib/gallery/updater.dart
@@ -6,7 +6,7 @@
 
 import 'package:url_launcher/url_launcher.dart';
 
-typedef UpdateUrlFetcher = Future<String> Function();
+typedef UpdateUrlFetcher = Future<String?> Function();
 
 class Updater extends StatefulWidget {
   const Updater({ required this.updateUrlFetcher, this.child, Key? key })
@@ -35,9 +35,9 @@
     }
     _lastUpdateCheck = DateTime.now();
 
-    final String updateUrl = await widget.updateUrlFetcher();
+    final String? updateUrl = await widget.updateUrlFetcher();
     final bool? wantsUpdate = await showDialog<bool>(context: context, builder: _buildDialog);
-    if (wantsUpdate != null && wantsUpdate)
+    if (wantsUpdate != null && updateUrl != null && wantsUpdate)
       launch(updateUrl);
   }
 
diff --git a/packages/flutter/lib/src/foundation/binding.dart b/packages/flutter/lib/src/foundation/binding.dart
index e6c650e..e140e87 100644
--- a/packages/flutter/lib/src/foundation/binding.dart
+++ b/packages/flutter/lib/src/foundation/binding.dart
@@ -236,12 +236,12 @@
             }
             _postExtensionStateChangedEvent(
               brightnessOverrideExtensionName,
-              (debugBrightnessOverride ?? platformDispatcher.platformBrightness).toString(),
+              (debugBrightnessOverride ?? window.platformBrightness).toString(),
             );
             await reassembleApplication();
           }
           return <String, dynamic>{
-            'value': (debugBrightnessOverride ?? platformDispatcher.platformBrightness).toString(),
+            'value': (debugBrightnessOverride ?? window.platformBrightness).toString(),
           };
         },
       );
diff --git a/packages/flutter/lib/src/gestures/binding.dart b/packages/flutter/lib/src/gestures/binding.dart
index 8b42ad0..7aa5f08 100644
--- a/packages/flutter/lib/src/gestures/binding.dart
+++ b/packages/flutter/lib/src/gestures/binding.dart
@@ -198,7 +198,7 @@
   void initInstances() {
     super.initInstances();
     _instance = this;
-    platformDispatcher.onPointerDataPacket = _handlePointerDataPacket;
+    window.onPointerDataPacket = _handlePointerDataPacket;
   }
 
   @override
diff --git a/packages/flutter/lib/src/rendering/binding.dart b/packages/flutter/lib/src/rendering/binding.dart
index 77d86db..e83bf5d 100644
--- a/packages/flutter/lib/src/rendering/binding.dart
+++ b/packages/flutter/lib/src/rendering/binding.dart
@@ -33,7 +33,7 @@
       onSemanticsOwnerCreated: _handleSemanticsOwnerCreated,
       onSemanticsOwnerDisposed: _handleSemanticsOwnerDisposed,
     );
-    platformDispatcher
+    window
       ..onMetricsChanged = handleMetricsChanged
       ..onTextScaleFactorChanged = handleTextScaleFactorChanged
       ..onPlatformBrightnessChanged = handlePlatformBrightnessChanged
@@ -280,7 +280,7 @@
   }
 
   void _handleSemanticsEnabledChanged() {
-    setSemanticsEnabled(platformDispatcher.semanticsEnabled);
+    setSemanticsEnabled(window.semanticsEnabled);
   }
 
   /// Whether the render tree associated with this binding should produce a tree
diff --git a/packages/flutter/lib/src/scheduler/binding.dart b/packages/flutter/lib/src/scheduler/binding.dart
index a57ac34..0fe1eca 100644
--- a/packages/flutter/lib/src/scheduler/binding.dart
+++ b/packages/flutter/lib/src/scheduler/binding.dart
@@ -265,10 +265,10 @@
   void addTimingsCallback(TimingsCallback callback) {
     _timingsCallbacks.add(callback);
     if (_timingsCallbacks.length == 1) {
-      assert(platformDispatcher.onReportTimings == null);
-      platformDispatcher.onReportTimings = _executeTimingsCallbacks;
+      assert(window.onReportTimings == null);
+      window.onReportTimings = _executeTimingsCallbacks;
     }
-    assert(platformDispatcher.onReportTimings == _executeTimingsCallbacks);
+    assert(window.onReportTimings == _executeTimingsCallbacks);
   }
 
   /// Removes a callback that was earlier added by [addTimingsCallback].
@@ -276,7 +276,7 @@
     assert(_timingsCallbacks.contains(callback));
     _timingsCallbacks.remove(callback);
     if (_timingsCallbacks.isEmpty) {
-      platformDispatcher.onReportTimings = null;
+      window.onReportTimings = null;
     }
   }
 
@@ -724,8 +724,8 @@
   /// [PlatformDispatcher.onDrawFrame] are registered.
   @protected
   void ensureFrameCallbacksRegistered() {
-    platformDispatcher.onBeginFrame ??= _handleBeginFrame;
-    platformDispatcher.onDrawFrame ??= _handleDrawFrame;
+    window.onBeginFrame ??= _handleBeginFrame;
+    window.onDrawFrame ??= _handleDrawFrame;
   }
 
   /// Schedules a new frame using [scheduleFrame] if this object is not
@@ -790,7 +790,7 @@
       return true;
     }());
     ensureFrameCallbacksRegistered();
-    platformDispatcher.scheduleFrame();
+    window.scheduleFrame();
     _hasScheduledFrame = true;
   }
 
@@ -827,7 +827,7 @@
         debugPrintStack(label: 'scheduleForcedFrame() called. Current phase is $schedulerPhase.');
       return true;
     }());
-    platformDispatcher.scheduleFrame();
+    window.scheduleFrame();
     _hasScheduledFrame = true;
   }
 
diff --git a/packages/flutter/lib/src/semantics/binding.dart b/packages/flutter/lib/src/semantics/binding.dart
index 62f9b82..131ff78 100644
--- a/packages/flutter/lib/src/semantics/binding.dart
+++ b/packages/flutter/lib/src/semantics/binding.dart
@@ -21,7 +21,7 @@
   void initInstances() {
     super.initInstances();
     _instance = this;
-    _accessibilityFeatures = platformDispatcher.accessibilityFeatures;
+    _accessibilityFeatures = window.accessibilityFeatures;
   }
 
   /// Called when the platform accessibility features change.
@@ -29,7 +29,7 @@
   /// See [dart:ui.PlatformDispatcher.onAccessibilityFeaturesChanged].
   @protected
   void handleAccessibilityFeaturesChanged() {
-    _accessibilityFeatures = platformDispatcher.accessibilityFeatures;
+    _accessibilityFeatures = window.accessibilityFeatures;
   }
 
   /// Creates an empty semantics update builder.
diff --git a/packages/flutter/lib/src/semantics/semantics.dart b/packages/flutter/lib/src/semantics/semantics.dart
index d30d1d7..f5fd3ab 100644
--- a/packages/flutter/lib/src/semantics/semantics.dart
+++ b/packages/flutter/lib/src/semantics/semantics.dart
@@ -2658,7 +2658,7 @@
       final CustomSemanticsAction action = CustomSemanticsAction.getAction(actionId)!;
       builder.updateCustomAction(id: actionId, label: action.label, hint: action.hint, overrideId: action.action?.index ?? -1);
     }
-    SemanticsBinding.instance!.platformDispatcher.updateSemantics(builder.build());
+    SemanticsBinding.instance!.window.updateSemantics(builder.build());
     notifyListeners();
   }
 
diff --git a/packages/flutter/lib/src/services/binding.dart b/packages/flutter/lib/src/services/binding.dart
index b4fa2c8..8992ba6 100644
--- a/packages/flutter/lib/src/services/binding.dart
+++ b/packages/flutter/lib/src/services/binding.dart
@@ -28,7 +28,7 @@
     _instance = this;
     _defaultBinaryMessenger = createBinaryMessenger();
     _restorationManager = createRestorationManager();
-    platformDispatcher.onPlatformMessage = defaultBinaryMessenger.handlePlatformMessage;
+    window.onPlatformMessage = defaultBinaryMessenger.handlePlatformMessage;
     initLicenses();
     SystemChannels.system.setMessageHandler((dynamic message) => handleSystemMessage(message as Object));
     SystemChannels.lifecycle.setMessageHandler(_handleLifecycleMessage);
diff --git a/packages/flutter/lib/src/widgets/app.dart b/packages/flutter/lib/src/widgets/app.dart
index 1a14c9c..2b4d801 100644
--- a/packages/flutter/lib/src/widgets/app.dart
+++ b/packages/flutter/lib/src/widgets/app.dart
@@ -1113,15 +1113,15 @@
   // If window.defaultRouteName isn't '/', we should assume it was set
   // intentionally via `setInitialRoute`, and should override whatever is in
   // [widget.initialRoute].
-  String get _initialRouteName => WidgetsBinding.instance!.platformDispatcher.defaultRouteName != Navigator.defaultRouteName
-    ? WidgetsBinding.instance!.platformDispatcher.defaultRouteName
-    : widget.initialRoute ?? WidgetsBinding.instance!.platformDispatcher.defaultRouteName;
+  String get _initialRouteName => WidgetsBinding.instance!.window.defaultRouteName != Navigator.defaultRouteName
+    ? WidgetsBinding.instance!.window.defaultRouteName
+    : widget.initialRoute ?? WidgetsBinding.instance!.window.defaultRouteName;
 
   @override
   void initState() {
     super.initState();
     _updateRouting();
-    _locale = _resolveLocales(WidgetsBinding.instance!.platformDispatcher.locales, widget.supportedLocales);
+    _locale = _resolveLocales(WidgetsBinding.instance!.window.locales, widget.supportedLocales);
     WidgetsBinding.instance!.addObserver(this);
   }
 
diff --git a/packages/flutter/lib/src/widgets/binding.dart b/packages/flutter/lib/src/widgets/binding.dart
index 22c4e08..c8a6cfd 100644
--- a/packages/flutter/lib/src/widgets/binding.dart
+++ b/packages/flutter/lib/src/widgets/binding.dart
@@ -245,7 +245,7 @@
   ///
   /// This method exposes notifications from
   /// [dart:ui.PlatformDispatcher.onLocaleChanged].
-  void didChangeLocales(List<Locale>? locale) { }
+  void didChangeLocales(List<Locale>? locales) { }
 
   /// Called when the system puts the app in the background or returns
   /// the app to the foreground.
@@ -287,8 +287,8 @@
     // properly setup the [defaultBinaryMessenger] instance.
     _buildOwner = BuildOwner();
     buildOwner!.onBuildScheduled = _handleBuildScheduled;
-    platformDispatcher.onLocaleChanged = handleLocaleChanged;
-    platformDispatcher.onAccessibilityFeaturesChanged = handleAccessibilityFeaturesChanged;
+    window.onLocaleChanged = handleLocaleChanged;
+    window.onAccessibilityFeaturesChanged = handleAccessibilityFeaturesChanged;
     SystemChannels.navigation.setMethodCallHandler(_handleNavigationInvocation);
     FlutterErrorDetails.propertiesTransformers.add(transformDebugCreator);
   }
@@ -586,7 +586,7 @@
   @protected
   @mustCallSuper
   void handleLocaleChanged() {
-    dispatchLocalesChanged(platformDispatcher.locales);
+    dispatchLocalesChanged(window.locales);
   }
 
   /// Notify all the observers that the locale has changed (using
@@ -1016,7 +1016,7 @@
   /// method again with the matched locale of the first call omitted from
   /// `supportedLocales`.
   Locale? computePlatformResolvedLocale(List<Locale> supportedLocales) {
-    return platformDispatcher.computePlatformResolvedLocale(supportedLocales);
+    return window.computePlatformResolvedLocale(supportedLocales);
   }
 }
 
diff --git a/packages/flutter/test/widgets/binding_first_frame_rasterized_test.dart b/packages/flutter/test/widgets/binding_first_frame_rasterized_test.dart
index 45eda8f..cb179de 100644
--- a/packages/flutter/test/widgets/binding_first_frame_rasterized_test.dart
+++ b/packages/flutter/test/widgets/binding_first_frame_rasterized_test.dart
@@ -19,14 +19,14 @@
 
       // Simulates the engine completing a frame render to trigger the
       // appropriate callback setting [WidgetBinding.firstFrameRasterized].
-      binding.platformDispatcher.onReportTimings!(<FrameTiming>[]);
+      binding.window.onReportTimings!(<FrameTiming>[]);
       expect(binding.firstFrameRasterized, isFalse);
 
       binding.allowFirstFrame();
       fakeAsync.flushTimers();
 
       // Simulates the engine again.
-      binding.platformDispatcher.onReportTimings!(<FrameTiming>[]);
+      binding.window.onReportTimings!(<FrameTiming>[]);
       expect(binding.firstFrameRasterized, isTrue);
     });
   });
diff --git a/packages/flutter_test/lib/src/binding.dart b/packages/flutter_test/lib/src/binding.dart
index d1714f0..dce1080 100644
--- a/packages/flutter_test/lib/src/binding.dart
+++ b/packages/flutter_test/lib/src/binding.dart
@@ -1039,8 +1039,8 @@
   @override
   void ensureFrameCallbacksRegistered() {
     // Leave PlatformDispatcher alone, do nothing.
-    assert(platformDispatcher.onDrawFrame == null);
-    assert(platformDispatcher.onBeginFrame == null);
+    assert(window.onDrawFrame == null);
+    assert(window.onBeginFrame == null);
   }
 
   @override
diff --git a/packages/flutter_test/test/window_test.dart b/packages/flutter_test/test/window_test.dart
index bfde8d8..0c9d037 100644
--- a/packages/flutter_test/test/window_test.dart
+++ b/packages/flutter_test/test/window_test.dart
@@ -5,7 +5,7 @@
 import 'dart:ui' as ui show window;
 import 'dart:ui' show Size, Locale, WindowPadding, AccessibilityFeatures, Brightness;
 
-import 'package:flutter/widgets.dart' show WidgetsBinding;
+import 'package:flutter/widgets.dart' show WidgetsBinding, WidgetsBindingObserver;
 import 'package:flutter_test/flutter_test.dart';
 
 void main() {
@@ -184,6 +184,14 @@
     expect(WidgetsBinding.instance!.window.devicePixelRatio, originalDevicePixelRatio);
     expect(WidgetsBinding.instance!.window.textScaleFactor, originalTextScaleFactor);
   });
+
+  testWidgets('TestWindow sends fake locales when WidgetsBindingObserver notifiers are called', (WidgetTester tester) async {
+    final TestObserver observer = TestObserver();
+    retrieveTestBinding(tester).addObserver(observer);
+    final List<Locale> expectedValue = <Locale>[const Locale('fake_language_code')];
+    retrieveTestBinding(tester).window.localesTestValue = expectedValue;
+    expect(observer.locales, equals(expectedValue));
+  });
 }
 
 void verifyThatTestWindowCanFakeProperty<WindowPropertyType>({
@@ -273,3 +281,13 @@
     return null;
   }
 }
+
+class TestObserver with WidgetsBindingObserver {
+  List<Locale>? locales;
+  Locale? locale;
+
+  @override
+  void didChangeLocales(List<Locale>? locales) {
+    this.locales = locales;
+  }
+}