Revert "Removes single window assumptions from flutter_test"

packages/flutter/lib/src/widgets/binding.dart

@@ -901,13 +901,15 @@ mixin WidgetsBinding on BindingBase, ServicesBinding, SchedulerBinding, GestureB
   /// Used by [runApp] to wrap the provided `rootWidget` in the default [View].
   ///
   /// The [View] determines into what [FlutterView] the app is rendered into.
-  /// This is currently [PlatformDispatcher.implicitView] from [platformDispatcher].
+  /// For backwards-compatibility reasons, this method currently chooses
+  /// [window] (which is a [FlutterView]) as the rendering target. This will
+  /// change in a future version of Flutter.
   ///
   /// The `rootWidget` widget provided to this method must not already be
   /// wrapped in a [View].
   Widget wrapWithDefaultView(Widget rootWidget) {
     return View(
-      view: platformDispatcher.implicitView!,
+      view: window,
       child: rootWidget,
     );
   }

packages/flutter/test/material/debug_test.dart

@@ -235,7 +235,7 @@ void main() {
       '     MediaQuery\n'
       '     _MediaQueryFromView\n'
       '     _ViewScope\n'
-      '     View-[GlobalObjectKey TestFlutterView#00000]\n'
+      '     View-[GlobalObjectKey TestWindow#00000]\n'
       '     [root]\n'
       '   Typically, the Scaffold widget is introduced by the MaterialApp\n'
       '   or WidgetsApp widget at the top of your application widget tree.\n'
@@ -376,7 +376,7 @@ void main() {
       '     MediaQuery\n'
       '     _MediaQueryFromView\n'
       '     _ViewScope\n'
-      '     View-[GlobalObjectKey TestFlutterView#00000]\n'
+      '     View-[GlobalObjectKey TestWindow#00000]\n'
       '     [root]\n'
       '   Typically, the ScaffoldMessenger widget is introduced by the\n'
       '   MaterialApp at the top of your application widget tree.\n'

packages/flutter/test/material/scaffold_test.dart

@@ -2454,7 +2454,7 @@ void main() {
       '     MediaQuery\n'
       '     _MediaQueryFromView\n'
       '     _ViewScope\n'
-      '     View-[GlobalObjectKey TestFlutterView#e6136]\n'
+      '     View-[GlobalObjectKey TestWindow#e6136]\n'
       '     [root]\n'
       '   Typically, the ScaffoldMessenger widget is introduced by the\n'
       '   MaterialApp at the top of your application widget tree.\n',

packages/flutter/test/widgets/custom_multi_child_layout_test.dart

@@ -374,7 +374,7 @@ void main() {
           '     creator: ConstrainedBox ← Container ← LayoutWithMissingId ←\n'
           '       CustomMultiChildLayout ← Center ← MediaQuery ←\n'
           '       _MediaQueryFromView ← _ViewScope ← View-[GlobalObjectKey\n'
-          '       TestFlutterView#00000] ← [root]\n'
+          '       TestWindow#00000] ← [root]\n'
           '     parentData: offset=Offset(0.0, 0.0); id=null\n'
           '     constraints: MISSING\n'
           '     size: MISSING\n'

packages/flutter/test/widgets/focus_manager_test.dart

@@ -1230,7 +1230,7 @@ void main() {
           ' │ primaryFocus: FocusNode#00000(Child 4 [PRIMARY FOCUS])\n'
           ' │ primaryFocusCreator: Container-[GlobalKey#00000] ← MediaQuery ←\n'
           ' │   _MediaQueryFromView ← _ViewScope ← View-[GlobalObjectKey\n'
-          ' │   TestFlutterView#00000] ← [root]\n'
+          ' │   TestWindow#00000] ← [root]\n'
           ' │\n'
           ' └─rootScope: FocusScopeNode#00000(Root Focus Scope [IN FOCUS PATH])\n'
           '   │ IN FOCUS PATH\n'

packages/flutter/test/widgets/slotted_render_object_widget_test.dart

@@ -223,15 +223,15 @@ void main() {
         '_RenderDiagonal#00000 relayoutBoundary=up1\n'
         ' │ creator: _Diagonal ← Align ← Directionality ← MediaQuery ←\n'
         ' │   _MediaQueryFromView ← _ViewScope ← View-[GlobalObjectKey\n'
-        ' │   TestFlutterView#00000] ← [root]\n'
+        ' │   TestWindow#00000] ← [root]\n'
         ' │ parentData: offset=Offset(0.0, 0.0) (can use size)\n'
         ' │ constraints: BoxConstraints(0.0<=w<=800.0, 0.0<=h<=600.0)\n'
         ' │ size: Size(190.0, 220.0)\n'
         ' │\n'
         ' ├─topLeft: RenderConstrainedBox#00000 relayoutBoundary=up2\n'
         ' │   creator: SizedBox ← _Diagonal ← Align ← Directionality ←\n'
         ' │     MediaQuery ← _MediaQueryFromView ← _ViewScope ←\n'
-        ' │     View-[GlobalObjectKey TestFlutterView#00000] ← [root]\n'
+        ' │     View-[GlobalObjectKey TestWindow#00000] ← [root]\n'
         ' │   parentData: offset=Offset(0.0, 0.0) (can use size)\n'
         ' │   constraints: BoxConstraints(unconstrained)\n'
         ' │   size: Size(80.0, 100.0)\n'
@@ -240,7 +240,7 @@ void main() {
         ' └─bottomRight: RenderConstrainedBox#00000 relayoutBoundary=up2\n'
         '     creator: SizedBox ← _Diagonal ← Align ← Directionality ←\n'
         '       MediaQuery ← _MediaQueryFromView ← _ViewScope ←\n'
-        '       View-[GlobalObjectKey TestFlutterView#00000] ← [root]\n'
+        '       View-[GlobalObjectKey TestWindow#00000] ← [root]\n'
         '     parentData: offset=Offset(80.0, 100.0) (can use size)\n'
         '     constraints: BoxConstraints(unconstrained)\n'
         '     size: Size(110.0, 120.0)\n'

packages/flutter_test/lib/src/binding.dart

@@ -182,18 +182,17 @@ abstract class TestWidgetsFlutterBinding extends BindingBase
   ///
   /// This constructor overrides the [debugPrint] global hook to point to
   /// [debugPrintOverride], which can be overridden by subclasses.
-  TestWidgetsFlutterBinding() : platformDispatcher = TestPlatformDispatcher(
-    platformDispatcher: PlatformDispatcher.instance,
-  ) {
+  TestWidgetsFlutterBinding() : _window = TestWindow(window: ui.window) {
     debugPrint = debugPrintOverride;
     debugDisableShadows = disableShadows;
   }
 
   @override
-  late final TestWindow window;
+  TestWindow get window => _window;
+  final TestWindow _window;
 
   @override
-  final TestPlatformDispatcher platformDispatcher;
+  TestPlatformDispatcher get platformDispatcher => _window.platformDispatcher;
 
   @override
   TestRestorationManager get restorationManager {
@@ -347,12 +346,6 @@ abstract class TestWidgetsFlutterBinding extends BindingBase
 
   @override
   void initInstances() {
-    // This is intialized here because it's needed for the `super.initInstances`
-    // call. It can't be handled as a ctor initializer because it's dependent
-    // on `platformDispatcher`. It can't be handled in the ctor itself because
-    // the base class ctor is called first and calls `initInstances`.
-    window = TestWindow.fromPlatformDispatcher(platformDispatcher: platformDispatcher);
-
     super.initInstances();
     _instance = this;
     timeDilation = 1.0; // just in case the developer has artificially changed it for development

packages/flutter_test/lib/src/controller.dart

@@ -14,7 +14,6 @@ import 'event_simulation.dart';
 import 'finders.dart';
 import 'test_async_utils.dart';
 import 'test_pointer.dart';
-import 'window.dart';
 
 /// The default drag touch slop used to break up a large drag into multiple
 /// smaller moves.
@@ -235,37 +234,6 @@ abstract class WidgetController {
   /// A reference to the current instance of the binding.
   final WidgetsBinding binding;
 
-  /// The [TestPlatformDispatcher] that is being used in this test.
-  ///
-  /// This will be injected into the framework such that calls to
-  /// [WidgetsBinding.platformDispatcher] will use this. This allows
-  /// users to change platform specific properties for testing.
-  ///
-  /// See also:
-  ///
-  ///   * [TestFlutterView] which allows changing view specific properties
-  ///     for testing
-  ///   * [view] and [viewOf] which are used to find
-  ///     [TestFlutterView]s from the widget tree
-  TestPlatformDispatcher get platformDispatcher => binding.platformDispatcher as TestPlatformDispatcher;
-
-  /// The [TestFlutterView] provided by default when testing with
-  /// [WidgetTester.pumpWidget].
-  ///
-  /// If the test requires multiple views, it will need to use [viewOf] instead
-  /// to ensure that the view related to the widget being evaluated is the one
-  /// that gets updated.
-  ///
-  /// See also:
-  ///
-  ///   * [viewOf], which can find a [TestFlutterView] related to a given finder.
-  ///     This is how to modify view properties for testing when dealing with
-  ///     multiple views.
-  TestFlutterView get view {
-    assert(platformDispatcher.views.length == 1, 'When testing with multiple views, use `viewOf` instead.');
-    return platformDispatcher.views.single;
-  }
-
   /// Provides access to a [SemanticsController] for testing anything related to
   /// the [Semantics] tree.
   ///
@@ -289,26 +257,6 @@ abstract class WidgetController {
   // TODO(ianh): verify that the return values are of type T and throw
   // a good message otherwise, in all the generic methods below
 
-  /// Finds the [TestFlutterView] that is the closest ancestor of the widget
-  /// found by [finder].
-  ///
-  /// [TestFlutterView] can be used to modify view specific properties for testing.
-  ///
-  /// See also:
-  ///
-  ///   * [view] which returns the [TestFlutterView] used when only a single
-  ///     view is being used.
-  TestFlutterView viewOf(Finder finder) {
-    final View view = firstWidget<View>(
-      find.ancestor(
-        of: finder,
-        matching: find.byType(View),
-      )
-    );
-
-    return view.view as TestFlutterView;
-  }
-
   /// Checks if `finder` exists in the tree.
   bool any(Finder finder) {
     TestAsyncUtils.guardSync();