Revert "[web] Remove the JS API for url strategy" (flutter/engine#42468)

Reverts flutter/engine#42134

This is blocking the engine into framework roller:

See: https://cirrus-ci.com/task/5610586755563520

```
Analyzing 3 items...                                            
  error • The class 'UrlStrategy' can't be extended outside of its library because it's an interface class • dev/integration_tests/web_e2e_tests/test_driver/url_strategy_integration.dart:48:31 • invalid_use_of_type_outside_library
1 issue found. (ran in 321.8s)
  🙙  🙛  
  ```

engine/src/flutter/ci/licenses_golden/licenses_flutter

@@ -1975,7 +1975,10 @@ ORIGIN: ../../../flutter/lib/web_ui/lib/src/engine/js_interop/js_typed_data.dart
 ORIGIN: ../../../flutter/lib/web_ui/lib/src/engine/key_map.g.dart + ../../../flutter/LICENSE
 ORIGIN: ../../../flutter/lib/web_ui/lib/src/engine/keyboard_binding.dart + ../../../flutter/LICENSE
 ORIGIN: ../../../flutter/lib/web_ui/lib/src/engine/mouse_cursor.dart + ../../../flutter/LICENSE
+ORIGIN: ../../../flutter/lib/web_ui/lib/src/engine/navigation.dart + ../../../flutter/LICENSE
 ORIGIN: ../../../flutter/lib/web_ui/lib/src/engine/navigation/history.dart + ../../../flutter/LICENSE
+ORIGIN: ../../../flutter/lib/web_ui/lib/src/engine/navigation/js_url_strategy.dart + ../../../flutter/LICENSE
+ORIGIN: ../../../flutter/lib/web_ui/lib/src/engine/navigation/url_strategy.dart + ../../../flutter/LICENSE
 ORIGIN: ../../../flutter/lib/web_ui/lib/src/engine/noto_font.dart + ../../../flutter/LICENSE
 ORIGIN: ../../../flutter/lib/web_ui/lib/src/engine/onscreen_logging.dart + ../../../flutter/LICENSE
 ORIGIN: ../../../flutter/lib/web_ui/lib/src/engine/picture.dart + ../../../flutter/LICENSE
@@ -4636,7 +4639,10 @@ FILE: ../../../flutter/lib/web_ui/lib/src/engine/js_interop/js_typed_data.dart
 FILE: ../../../flutter/lib/web_ui/lib/src/engine/key_map.g.dart
 FILE: ../../../flutter/lib/web_ui/lib/src/engine/keyboard_binding.dart
 FILE: ../../../flutter/lib/web_ui/lib/src/engine/mouse_cursor.dart
+FILE: ../../../flutter/lib/web_ui/lib/src/engine/navigation.dart
 FILE: ../../../flutter/lib/web_ui/lib/src/engine/navigation/history.dart
+FILE: ../../../flutter/lib/web_ui/lib/src/engine/navigation/js_url_strategy.dart
+FILE: ../../../flutter/lib/web_ui/lib/src/engine/navigation/url_strategy.dart
 FILE: ../../../flutter/lib/web_ui/lib/src/engine/noto_font.dart
 FILE: ../../../flutter/lib/web_ui/lib/src/engine/onscreen_logging.dart
 FILE: ../../../flutter/lib/web_ui/lib/src/engine/picture.dart

engine/src/flutter/lib/web_ui/lib/src/engine.dart

@@ -113,6 +113,8 @@ export 'engine/key_map.g.dart';
 export 'engine/keyboard_binding.dart';
 export 'engine/mouse_cursor.dart';
 export 'engine/navigation/history.dart';
+export 'engine/navigation/js_url_strategy.dart';
+export 'engine/navigation/url_strategy.dart';
 export 'engine/noto_font.dart';
 export 'engine/onscreen_logging.dart';
 export 'engine/picture.dart';

engine/src/flutter/lib/web_ui/lib/src/engine/initialization.dart

@@ -8,6 +8,7 @@ import 'dart:js_interop';
 
 import 'package:ui/src/engine.dart';
 import 'package:ui/ui.dart' as ui;
+import 'package:ui/ui_web/src/ui_web.dart' as ui_web;
 import 'package:web_test_fonts/web_test_fonts.dart';
 
 /// The mode the app is running in.
@@ -132,6 +133,10 @@ Future<void> initializeEngineServices({
   // Store `jsConfiguration` so user settings are available to the engine.
   configuration.setUserConfiguration(jsConfiguration);
 
+  // Setup the hook that allows users to customize URL strategy before running
+  // the app.
+  _addUrlStrategyListener();
+
   // Called by the Web runtime just before hot restarting the app.
   //
   // This extension cleans up resources that are registered with browser's
@@ -258,6 +263,26 @@ Future<void> _downloadAssetFonts() async {
   }
 }
 
+void _addUrlStrategyListener() {
+  jsSetUrlStrategy = allowInterop((JsUrlStrategy? jsStrategy) {
+    if (jsStrategy == null) {
+      ui_web.urlStrategy = null;
+    } else {
+      // Because `JSStrategy` could be anything, we check for the
+      // `addPopStateListener` property and throw if it is missing.
+      if (!hasJsProperty(jsStrategy, 'addPopStateListener')) {
+        throw StateError(
+            'Unexpected JsUrlStrategy: $jsStrategy is missing '
+            '`addPopStateListener` property');
+      }
+      ui_web.urlStrategy = CustomUrlStrategy.fromJs(jsStrategy);
+    }
+  });
+  registerHotRestartListener(() {
+    jsSetUrlStrategy = null;
+  });
+}
+
 /// Whether to disable the font fallback system.
 ///
 /// We need to disable font fallbacks for some framework tests because

engine/src/flutter/lib/web_ui/lib/src/engine/navigation.dart

@@ -0,0 +1,7 @@
+// Copyright 2013 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 'navigation/history.dart';
+export 'navigation/js_url_strategy.dart';
+export 'navigation/url_strategy.dart';

engine/src/flutter/lib/web_ui/lib/src/engine/navigation/js_url_strategy.dart

@@ -0,0 +1,87 @@
+// Copyright 2013 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.
+
+@JS()
+library js_url_strategy;
+
+import 'dart:js_interop';
+
+import 'package:ui/ui.dart' as ui;
+
+import '../dom.dart';
+
+typedef _PathGetter = String Function();
+
+typedef _StateGetter = Object? Function();
+
+typedef _AddPopStateListener = ui.VoidCallback Function(DartDomEventListener);
+
+typedef _StringToString = String Function(String);
+
+typedef _StateOperation = void Function(
+    Object? state, String title, String url);
+
+typedef _HistoryMove = Future<void> Function(double count);
+
+/// The JavaScript representation of a URL strategy.
+///
+/// This is used to pass URL strategy implementations across a JS-interop
+/// bridge from the app to the engine.
+@JS()
+@anonymous
+@staticInterop
+abstract class JsUrlStrategy {
+  /// Creates an instance of [JsUrlStrategy] from a bag of URL strategy
+  /// functions.
+  external factory JsUrlStrategy({
+    required _PathGetter getPath,
+    required _StateGetter getState,
+    required _AddPopStateListener addPopStateListener,
+    required _StringToString prepareExternalUrl,
+    required _StateOperation pushState,
+    required _StateOperation replaceState,
+    required _HistoryMove go,
+  });
+}
+
+extension JsUrlStrategyExtension on JsUrlStrategy {
+  /// Adds a listener to the `popstate` event and returns a function that, when
+  /// invoked, removes the listener.
+  external ui.VoidCallback addPopStateListener(DartDomEventListener fn);
+
+  /// Returns the active path in the browser.
+  external String getPath();
+
+  /// Returns the history state in the browser.
+  ///
+  /// See: https://developer.mozilla.org/en-US/docs/Web/API/History/state
+  external Object? getState();
+
+  /// Given a path that's internal to the app, create the external url that
+  /// will be used in the browser.
+  external String prepareExternalUrl(String internalUrl);
+
+  /// Push a new history entry.
+  ///
+  /// See: https://developer.mozilla.org/en-US/docs/Web/API/History/pushState
+  external void pushState(Object? state, String title, String url);
+
+  /// Replace the currently active history entry.
+  ///
+  /// See: https://developer.mozilla.org/en-US/docs/Web/API/History/replaceState
+  external void replaceState(Object? state, String title, String url);
+
+  /// Moves forwards or backwards through the history stack.
+  ///
+  /// A negative [count] value causes a backward move in the history stack. And
+  /// a positive [count] value causs a forward move.
+  ///
+  /// Examples:
+  ///
+  /// * `go(-2)` moves back 2 steps in history.
+  /// * `go(3)` moves forward 3 steps in hisotry.
+  ///
+  /// See: https://developer.mozilla.org/en-US/docs/Web/API/History/go
+  external Future<void> go(double count);
+}

engine/src/flutter/lib/web_ui/lib/src/engine/navigation/url_strategy.dart

@@ -0,0 +1,48 @@
+// Copyright 2013 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.
+
+import 'dart:async';
+
+import 'package:ui/ui.dart' as ui;
+import 'package:ui/ui_web/src/ui_web.dart' as ui_web;
+
+import '../dom.dart';
+import '../safe_browser_api.dart';
+import 'js_url_strategy.dart';
+
+/// Wraps a custom implementation of [ui_web.UrlStrategy] that was previously converted
+/// to a [JsUrlStrategy].
+class CustomUrlStrategy extends ui_web.UrlStrategy {
+  /// Wraps the [delegate] in a [CustomUrlStrategy] instance.
+  CustomUrlStrategy.fromJs(this.delegate);
+
+  final JsUrlStrategy delegate;
+
+  @override
+  ui.VoidCallback addPopStateListener(ui_web.PopStateListener fn) =>
+      delegate.addPopStateListener(allowInterop((DomEvent event) =>
+        fn((event as DomPopStateEvent).state)
+      ));
+
+  @override
+  String getPath() => delegate.getPath();
+
+  @override
+  Object? getState() => delegate.getState();
+
+  @override
+  String prepareExternalUrl(String internalUrl) =>
+      delegate.prepareExternalUrl(internalUrl);
+
+  @override
+  void pushState(Object? state, String title, String url) =>
+      delegate.pushState(state, title, url);
+
+  @override
+  void replaceState(Object? state, String title, String url) =>
+      delegate.replaceState(state, title, url);
+
+  @override
+  Future<void> go(int count) => delegate.go(count.toDouble());
+}

engine/src/flutter/lib/web_ui/lib/src/engine/test_embedding.dart

@@ -30,7 +30,7 @@ class TestHistoryEntry {
 ///
 /// It keeps a list of history entries and event listeners in memory and
 /// manipulates them in order to achieve the desired functionality.
-class TestUrlStrategy implements ui_web.UrlStrategy {
+class TestUrlStrategy extends ui_web.UrlStrategy {
   /// Creates a instance of [TestUrlStrategy] with an empty string as the
   /// path.
   factory TestUrlStrategy() => TestUrlStrategy.fromEntry(const TestHistoryEntry(null, null, ''));

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

@@ -16,6 +16,7 @@ import 'package:ui/ui_web/src/ui_web.dart' as ui_web;
 import '../engine.dart' show DimensionsProvider, registerHotRestartListener, renderer;
 import 'dom.dart';
 import 'navigation/history.dart';
+import 'navigation/js_url_strategy.dart';
 import 'platform_dispatcher.dart';
 import 'services.dart';
 import 'util.dart';
@@ -323,6 +324,16 @@ class EngineFlutterWindow extends ui.SingletonFlutterWindow {
   ui.Size? webOnlyDebugPhysicalSizeOverride;
 }
 
+typedef _JsSetUrlStrategy = void Function(JsUrlStrategy?);
+
+/// A JavaScript hook to customize the URL strategy of a Flutter app.
+//
+// DO NOT CHANGE THE JS NAME, IT IS PUBLIC API AT THIS POINT.
+//
+// TODO(mdebbar): Add integration test https://github.com/flutter/flutter/issues/66852
+@JS('_flutter_web_set_location_strategy')
+external set jsSetUrlStrategy(_JsSetUrlStrategy? newJsSetUrlStrategy);
+
 /// The Web implementation of [ui.SingletonFlutterWindow].
 class EngineSingletonFlutterWindow extends EngineFlutterWindow {
   EngineSingletonFlutterWindow(

engine/src/flutter/lib/web_ui/lib/ui_web/src/ui_web/navigation/url_strategy.dart

@@ -82,7 +82,11 @@ typedef PopStateListener = void Function(Object? state);
 ///
 /// By default, the [HashUrlStrategy] subclass is used if the app doesn't
 /// specify one.
-abstract interface class UrlStrategy {
+abstract class UrlStrategy {
+  /// Abstract const constructor. This constructor enables subclasses to provide
+  /// const constructors so that they can be used in const expressions.
+  const UrlStrategy();
+
   /// Adds a listener to the `popstate` event and returns a function that, when
   /// invoked, removes the listener.
   ui.VoidCallback addPopStateListener(PopStateListener fn);
@@ -135,7 +139,7 @@ abstract interface class UrlStrategy {
 /// // Somewhere before calling `runApp()` do:
 /// setUrlStrategy(const HashUrlStrategy());
 /// ```
-class HashUrlStrategy implements UrlStrategy {
+class HashUrlStrategy extends UrlStrategy {
   /// Creates an instance of [HashUrlStrategy].
   ///
   /// The [PlatformLocation] parameter is useful for testing to mock out browser

engine/src/flutter/lib/web_ui/test/engine/history_test.dart

@@ -8,8 +8,9 @@ import 'package:quiver/testing/async.dart';
 import 'package:test/bootstrap/browser.dart';
 import 'package:test/test.dart';
 import 'package:ui/src/engine.dart' show window;
-import 'package:ui/src/engine/dom.dart' show DomEvent, createDomPopStateEvent;
-import 'package:ui/src/engine/navigation/history.dart';
+import 'package:ui/src/engine/dom.dart'
+    show DomEvent, createDomPopStateEvent;
+import 'package:ui/src/engine/navigation.dart';
 import 'package:ui/src/engine/services.dart';
 import 'package:ui/src/engine/test_embedding.dart';
 import 'package:ui/ui_web/src/ui_web.dart';

engine/src/flutter/lib/web_ui/test/engine/routing_test.dart

@@ -3,12 +3,12 @@
 // found in the LICENSE file.
 
 import 'dart:async';
+import 'dart:js_util' as js_util;
 
 import 'package:test/bootstrap/browser.dart';
 import 'package:test/test.dart';
 import 'package:ui/src/engine.dart' hide window;
 import 'package:ui/ui.dart' as ui;
-import 'package:ui/ui_web/src/ui_web.dart' as ui_web;
 
 import '../common/matchers.dart';
 import 'history_test.dart';
@@ -48,15 +48,27 @@ void testMain() {
     expect(window.viewId, 0);
   });
 
-  test('window.defaultRouteName should work with a custom url strategy', () async {
-    const String path = '/initial';
-    const Object state = <dynamic, dynamic>{'origin': true};
-
-    final _SampleUrlStrategy customStrategy = _SampleUrlStrategy(path, state);
-    await window.debugInitializeHistory(customStrategy, useSingle: true);
+  test('window.defaultRouteName should work with JsUrlStrategy', () async {
+    dynamic state = <dynamic, dynamic>{};
+    final JsUrlStrategy jsUrlStrategy = JsUrlStrategy(
+        getPath: allowInterop(() => '/initial'),
+        getState: allowInterop(() => state),
+        addPopStateListener: allowInterop((DartDomEventListener listener) => allowInterop(() {})),
+        prepareExternalUrl: allowInterop((String value) => ''),
+        pushState: allowInterop((Object? newState, String title, String url) {
+          expect(newState is Map, true);
+        }),
+        replaceState: allowInterop((Object? newState, String title, String url) {
+          expect(newState is Map, true);
+          state = newState;
+        }),
+        go: allowInterop(([double? delta]) async {
+          expect(delta, -1);
+        }));
+    final CustomUrlStrategy strategy =
+        CustomUrlStrategy.fromJs(jsUrlStrategy);
+    await window.debugInitializeHistory(strategy, useSingle: true);
     expect(window.defaultRouteName, '/initial');
-    // Also make sure that the custom url strategy was actually used.
-    expect(customStrategy.wasUsed, isTrue);
   });
 
   test('window.defaultRouteName should not change', () async {
@@ -429,12 +441,7 @@ void testMain() {
 
   test('can disable location strategy', () async {
     // Disable URL strategy.
-    expect(
-      () {
-        ui_web.urlStrategy = null;
-      },
-      returnsNormally,
-    );
+    expect(() => jsSetUrlStrategy(null), returnsNormally);
     // History should be initialized.
     expect(window.browserHistory, isNotNull);
     // But without a URL strategy.
@@ -448,35 +455,27 @@ void testMain() {
     expect(window.browserHistory.currentPath, '/');
   });
 
-  test('cannot set url strategy after it was initialized', () async {
+  test('js interop throws on wrong type', () {
+    expect(() => jsSetUrlStrategy(123), throwsA(anything));
+    expect(() => jsSetUrlStrategy('foo'), throwsA(anything));
+    expect(() => jsSetUrlStrategy(false), throwsA(anything));
+    expect(() => jsSetUrlStrategy(<Object?>[]), throwsA(anything));
+  });
+
+  test('cannot set url strategy after it is initialized', () async {
     final TestUrlStrategy testStrategy = TestUrlStrategy.fromEntry(
       const TestHistoryEntry('initial state', null, '/'),
     );
     await window.debugInitializeHistory(testStrategy, useSingle: true);
 
-    expect(
-      () {
-        ui_web.urlStrategy = null;
-      },
-      throwsA(isAssertionError),
-    );
+    expect(() => jsSetUrlStrategy(null), throwsA(isAssertionError));
   });
 
   test('cannot set url strategy more than once', () async {
     // First time is okay.
-    expect(
-      () {
-        ui_web.urlStrategy = null;
-      },
-      returnsNormally,
-    );
+    expect(() => jsSetUrlStrategy(null), returnsNormally);
     // Second time is not allowed.
-    expect(
-      () {
-        ui_web.urlStrategy = null;
-      },
-      throwsA(isAssertionError),
-    );
+    expect(() => jsSetUrlStrategy(null), throwsA(isAssertionError));
   });
 
   // Regression test for https://github.com/flutter/flutter/issues/77817
@@ -487,41 +486,10 @@ void testMain() {
   });
 }
 
-class _SampleUrlStrategy implements ui_web.UrlStrategy {
-  _SampleUrlStrategy(this._path, this._state);
-
-  final String _path;
-  final Object? _state;
-
-  bool wasUsed = false;
-
-  @override
-  String getPath() => _path;
-
-  @override
-  Object? getState() => _state;
-
-  @override
-  ui.VoidCallback addPopStateListener(DartDomEventListener listener) {
-    wasUsed = true;
-    return () {};
-  }
-
-  @override
-  String prepareExternalUrl(String value) => '';
-
-  @override
-  void pushState(Object? newState, String title, String url) {
-    wasUsed = true;
-  }
-
-  @override
-  void replaceState(Object? newState, String title, String url) {
-    wasUsed = true;
-  }
-
-  @override
-  Future<void> go(int delta) async {
-    wasUsed = true;
-  }
+void jsSetUrlStrategy(dynamic strategy) {
+  js_util.callMethod<void>(
+    domWindow,
+    '_flutter_web_set_location_strategy',
+    <dynamic>[strategy],
+  );
 }