[web] Rename EngineFlutterWindow => EngineSingletonFlutterWindow

lib/web_ui/lib/src/engine/platform_dispatcher.dart

@@ -171,7 +171,8 @@ class EnginePlatformDispatcher extends ui.PlatformDispatcher {
   /// * [PlatformDisptacher.views] for a list of all [FlutterView]s provided
   ///   by the platform.
   @override
-  EngineFlutterWindow? get implicitView => viewData[kImplicitViewId] as EngineFlutterWindow?;
+  EngineSingletonFlutterWindow? get implicitView =>
+      viewData[kImplicitViewId] as EngineSingletonFlutterWindow?;
 
   /// A callback that is invoked whenever the platform's [devicePixelRatio],
   /// [physicalSize], [padding], [viewInsets], or [systemGestureInsets]

lib/web_ui/lib/src/engine/window.dart

@@ -41,8 +41,8 @@ abstract interface class EngineFlutterView extends ui.FlutterView {
 }
 
 /// The Web implementation of [ui.SingletonFlutterWindow].
-class EngineFlutterWindow extends ui.SingletonFlutterWindow implements EngineFlutterView {
-  EngineFlutterWindow(this.viewId, this.platformDispatcher) {
+class EngineSingletonFlutterWindow extends ui.SingletonFlutterWindow implements EngineFlutterView {
+  EngineSingletonFlutterWindow(this.viewId, this.platformDispatcher) {
     platformDispatcher.viewData[viewId] = this;
     platformDispatcher.windowConfigurations[viewId] = const ViewConfiguration();
     if (ui_web.isCustomUrlStrategySet) {
@@ -383,8 +383,10 @@ class EngineFlutterWindow extends ui.SingletonFlutterWindow implements EngineFlu
 /// `dart:ui` window delegates to this value. However, this value has a wider
 /// API surface, providing Web-specific functionality that the standard
 /// `dart:ui` version does not.
-final EngineFlutterWindow window =
-    EngineFlutterWindow(kImplicitViewId, EnginePlatformDispatcher.instance);
+final EngineSingletonFlutterWindow window = EngineSingletonFlutterWindow(
+  kImplicitViewId,
+  EnginePlatformDispatcher.instance,
+);
 
 /// The Web implementation of [ui.ViewPadding].
 class ViewPadding implements ui.ViewPadding {

lib/web_ui/lib/ui_web/src/ui_web/testing.dart

@@ -8,7 +8,7 @@ import 'package:ui/ui.dart' as ui;
 extension SingletonFlutterWindowExtension on ui.SingletonFlutterWindow {
   /// Overrides the value of [physicalSize] in tests.
   set debugPhysicalSizeOverride(ui.Size? value) {
-    (this as EngineFlutterWindow).debugPhysicalSizeOverride = value;
+    (this as EngineSingletonFlutterWindow).debugPhysicalSizeOverride = value;
   }
 }
 

lib/web_ui/test/engine/routing_test.dart

@@ -27,14 +27,14 @@ void main() {
 }
 
 void testMain() {
-  late EngineFlutterWindow window;
+  late EngineSingletonFlutterWindow window;
 
   setUpAll(() async {
     await initializeEngine();
   });
 
   setUp(() {
-    window = EngineFlutterWindow(0, EnginePlatformDispatcher.instance);
+    window = EngineSingletonFlutterWindow(0, EnginePlatformDispatcher.instance);
   });
 
   tearDown(() async {

lib/web_ui/test/engine/surface/platform_view_test.dart

@@ -13,7 +13,8 @@ import 'package:ui/ui_web/src/ui_web.dart' as ui_web;
 import '../../common/matchers.dart';
 
 const MethodCodec codec = StandardMethodCodec();
-final EngineFlutterWindow window = EngineFlutterWindow(0, EnginePlatformDispatcher.instance);
+final EngineSingletonFlutterWindow window =
+    EngineSingletonFlutterWindow(0, EnginePlatformDispatcher.instance);
 
 void main() {
   internalBootstrapBrowserTest(() => testMain);