[web] ui.platformViewRegistry => ui_web.platformViewRegistry (#127493)

Now that `platformViewRegistry` is [exposed](https://github.com/flutter/engine/pull/41877) through `dart:ui_web`, we can do some cleanup here.

Part of https://github.com/flutter/flutter/issues/126831

dev/benchmarks/macrobenchmarks/lib/src/draw_points.dart

@@ -3,11 +3,10 @@
 // found in the LICENSE file.
 
 import 'dart:typed_data';
+import 'dart:ui';
 
 import 'package:flutter/material.dart';
 
-import 'web/platform_views/web.dart';
-
 class DrawPointsPage extends StatefulWidget  {
   const DrawPointsPage({super.key});
 

dev/benchmarks/macrobenchmarks/lib/src/web/bench_platform_view_infinite_scroll.dart

@@ -4,19 +4,16 @@
 
 import 'dart:async';
 import 'dart:html' as html;
+import 'dart:ui_web' as ui_web;
 
 import 'package:flutter/material.dart';
 
-// TODO(mdebbar): flutter/flutter#55000 Remove this conditional import once
-// web-only dart:ui_web APIs are exposed from a dedicated place.
-import 'platform_views/non_web.dart'
-    if (dart.library.html) 'platform_views/web.dart';
 import 'recorder.dart';
 
 const String benchmarkViewType = 'benchmark_element';
 
 void _registerFactory() {
-  platformViewRegistry.registerViewFactory(benchmarkViewType, (int viewId) {
+  ui_web.platformViewRegistry.registerViewFactory(benchmarkViewType, (int viewId) {
     final html.Element htmlElement = html.DivElement();
     htmlElement.id = '${benchmarkViewType}_$viewId';
     htmlElement.innerText = 'Google';

dev/benchmarks/macrobenchmarks/lib/src/web/platform_views/non_web.dart

-// Copyright 2014 The Flutter Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-// ignore: avoid_classes_with_only_static_members
-/// Shim for web_ui engine.PlatformViewRegistry
-/// https://github.com/flutter/engine/blob/master/lib/web_ui/lib/ui.dart#L62
-// ignore: camel_case_types
-class platformViewRegistry {
-  /// Shim for registerViewFactory
-  /// https://github.com/flutter/engine/blob/master/lib/web_ui/lib/ui.dart#L72
-  static void registerViewFactory(
-      String viewTypeId, dynamic Function(int viewId) viewFactory,
-      {bool isVisible = true}) {}
-}

dev/benchmarks/macrobenchmarks/lib/src/web/platform_views/web.dart

-// Copyright 2014 The Flutter Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-export 'dart:ui';

dev/integration_tests/web_e2e_tests/test_driver/platform_messages_integration.dart

@@ -3,8 +3,7 @@
 // found in the LICENSE file.
 
 import 'dart:html' as html;
-// platformViewRegistry is exposed in the web version
-import 'dart:ui' as ui show platformViewRegistry; // ignore: undefined_shown_name
+import 'dart:ui_web' as ui_web;
 
 import 'package:flutter/material.dart';
 import 'package:flutter/services.dart';
@@ -37,8 +36,7 @@ void main() {
     int viewInstanceCount = 0;
 
     platformViewsRegistry.getNextPlatformViewId();
-    // ignore: undefined_prefixed_name, avoid_dynamic_calls
-    ui.platformViewRegistry.registerViewFactory('MyView', (int viewId) {
+    ui_web.platformViewRegistry.registerViewFactory('MyView', (int viewId) {
       viewInstanceCount += 1;
       return html.DivElement();
     });

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

@@ -9,6 +9,10 @@
 import 'framework.dart';
 import 'selection_container.dart';
 
+/// Function signature for `ui_web.platformViewRegistry.registerViewFactory`.
+@visibleForTesting
+typedef RegisterViewFactory = void Function(String, Object Function(int viewId), {bool isVisible});
+
 /// A widget that provides native selection context menu for its child subtree.
 ///
 /// This widget currently only supports Flutter web. Using this widget in non-web
@@ -36,6 +40,12 @@ class PlatformSelectableRegionContextMenu extends StatelessWidget {
   /// Detaches the `client` from the platform-appropriate selection context menus.
   static void detach(SelectionContainerDelegate client) => throw UnimplementedError();
 
+  /// Override this to provide a custom implementation of `ui_web.platformViewRegistry.registerViewFactory`.
+  ///
+  /// This should only be used for testing.
+  @visibleForTesting
+  static RegisterViewFactory? debugOverrideRegisterViewFactory;
+
   @override
   Widget build(BuildContext context) => throw UnimplementedError();
 }

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

@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-import 'dart:ui' as ui;
+import 'dart:ui_web' as ui_web;
 
 import 'package:flutter/rendering.dart';
 
@@ -29,7 +29,7 @@ const int _kRightClickButton = 2;
 
 typedef _WebSelectionCallBack = void Function(DomHTMLElement, DomMouseEvent);
 
-/// Function signature for `ui.platformViewRegistry.registerViewFactory`.
+/// Function signature for `ui_web.platformViewRegistry.registerViewFactory`.
 @visibleForTesting
 typedef RegisterViewFactory = void Function(String, Object Function(int viewId), {bool isVisible});
 
@@ -67,10 +67,15 @@ class PlatformSelectableRegionContextMenu extends StatelessWidget {
   // Keeps track if this widget has already registered its view factories or not.
   static String? _registeredViewType;
 
-  /// See `_platform_selectable_region_context_menu_io.dart`.
+  static RegisterViewFactory get _registerViewFactory =>
+      debugOverrideRegisterViewFactory ?? ui_web.platformViewRegistry.registerViewFactory;
+
+  /// Override this to provide a custom implementation of [ui_web.platformViewRegistry.registerViewFactory].
+  ///
+  /// This should only be used for testing.
+  // See `_platform_selectable_region_context_menu_io.dart`.
   @visibleForTesting
-  // ignore: undefined_prefixed_name, invalid_assignment, avoid_dynamic_calls
-  static RegisterViewFactory registerViewFactory = ui.platformViewRegistry.registerViewFactory;
+  static RegisterViewFactory? debugOverrideRegisterViewFactory;
 
   // Registers the view factories for the interceptor widgets.
   static void _register() {
@@ -100,7 +105,7 @@ class PlatformSelectableRegionContextMenu extends StatelessWidget {
   }
 
   static String _registerWebSelectionCallback(_WebSelectionCallBack callback) {
-    registerViewFactory(_viewType, (int viewId) {
+    _registerViewFactory(_viewType, (int viewId) {
       final DomHTMLElement htmlElement = createDomHTMLDivElement();
       htmlElement
         ..style.width = '100%'

packages/flutter/test/widgets/selectable_region_context_menu_test.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.
 
-// ignore_for_file: undefined_class, undefined_getter, undefined_setter
-
 @TestOn('browser') // This file contains web-only library.
 library;
 
@@ -16,8 +14,7 @@ import 'package:flutter_test/flutter_test.dart';
 
 void main() {
   html.Element? element;
-  final RegisterViewFactory originalFactory = PlatformSelectableRegionContextMenu.registerViewFactory;
-  PlatformSelectableRegionContextMenu.registerViewFactory = (String viewType, Object Function(int viewId) fn, {bool isVisible = true}) {
+  PlatformSelectableRegionContextMenu.debugOverrideRegisterViewFactory = (String viewType, Object Function(int viewId) fn, {bool isVisible = true}) {
     element = fn(0) as html.Element;
     // The element needs to be attached to the document body to receive mouse
     // events.
@@ -25,7 +22,7 @@ void main() {
   };
   // This force register the dom element.
   PlatformSelectableRegionContextMenu(child: const Placeholder());
-  PlatformSelectableRegionContextMenu.registerViewFactory = originalFactory;
+  PlatformSelectableRegionContextMenu.debugOverrideRegisterViewFactory = null;
 
   test('DOM element is set up correctly', () async {
     expect(element, isNotNull);