Clean up 'flutter run' output. (#6610)

Fixes #4166.
Fixes #5120.
Fixes #5399.
Fixes #6507.

packages/flutter_tools/lib/src/run.dart

diff --git a/packages/flutter_tools/lib/src/run.dart b/packages/flutter_tools/lib/src/run.dart
index 2fd0ea5..216253f 100644
--- a/packages/flutter_tools/lib/src/run.dart
+++ b/packages/flutter_tools/lib/src/run.dart
@@ -5,6 +5,7 @@
 import 'dart:async';
 import 'dart:io';
 
+import 'package:meta/meta.dart';
 import 'package:stack_trace/stack_trace.dart';
 
 import 'application_package.dart';
@@ -197,13 +198,13 @@
       }
     }
 
-    printStatus('Application running.');
+    printTrace('Application running.');
     if (debuggingOptions.buildMode == BuildMode.release)
       return 0;
 
     if (vmService != null) {
       await vmService.vm.refreshViews();
-      printStatus('Connected to ${vmService.vm.mainView}\.');
+      printTrace('Connected to ${vmService.vm.mainView}\.');
     }
 
     if (vmService != null && traceStartup) {
@@ -261,11 +262,18 @@
   }
 
   @override
-  void printHelp() {
-    final bool showRestartText = !prebuiltMode && device.supportsRestart;
-    String restartText = showRestartText ? ', "r" or F5 to restart the app,' : '';
-    printStatus('Type "h" or F1 for help$restartText and "q", F10, or ctrl-c to quit.');
-    printStatus('Type "w" to print the widget hierarchy of the app, and "t" for the render tree.');
+  void printHelp({ @required bool details }) {
+    if (!prebuiltMode && device.supportsRestart)
+      printStatus('To restart the app, press "r" or F5.');
+    if (_result.hasObservatory)
+      printStatus('The Observatory debugger and profiler is available at: http://127.0.0.1:${_result.observatoryPort}/');
+    if (details) {
+      printStatus('To dump the widget hierarchy of the app (debugDumpApp), press "w".');
+      printStatus('To dump the rendering tree of the app (debugDumpRenderTree), press "r".');
+      printStatus('To repeat this help message, press "h" or F1. To quit, press "q", F10, or Ctrl-C.');
+    } else {
+      printStatus('For a more detailed help message, press "h" or F1. To quit, press "q", F10, or Ctrl-C.');
+    }
   }
 }