[webview_flutter] Implement platform interface for JavaScript dialog (flutter#5670)

Adds the platform interface implementation for JavaScript dailog.

This PR is part of a series of PRs that aim to close flutter#30358 (comment)
The PR that contains all changes can be found at flutter/packages#4704

Author: jsharp83

packages/webview_flutter/webview_flutter_platform_interface/CHANGELOG.md

@@ -1,3 +1,7 @@
+## 2.9.0
+
+* Adds support to show JavaScript dialog. See `PlatformWebViewController.setOnJavaScriptAlertDialog`, `PlatformWebViewController.setOnJavaScriptConfirmDialog` and `PlatformWebViewController.setOnJavaScriptTextInputDialog`.
+
 ## 2.8.0
 
 * Adds support to track scroll position changes. See `PlatformWebViewController.setOnScrollPositionChange`.

packages/webview_flutter/webview_flutter_platform_interface/lib/src/platform_webview_controller.dart

@@ -294,6 +294,36 @@ abstract class PlatformWebViewController extends PlatformInterface {
     throw UnimplementedError(
         'setOnScrollPositionChange is not implemented on the current platform');
   }
+
+  /// Sets a callback that notifies the host application that the web page
+  /// wants to display a JavaScript alert() dialog.
+  Future<void> setOnJavaScriptAlertDialog(
+      Future<void> Function(JavaScriptAlertDialogRequest request)
+          onJavaScriptAlertDialog) async {
+    throw UnimplementedError(
+      'setOnJavaScriptAlertDialog is not implemented on the current platform',
+    );
+  }
+
+  /// Sets a callback that notifies the host application that the web page
+  /// wants to display a JavaScript confirm() dialog.
+  Future<void> setOnJavaScriptConfirmDialog(
+      Future<bool> Function(JavaScriptConfirmDialogRequest request)
+          onJavaScriptConfirmDialog) async {
+    throw UnimplementedError(
+      'setOnJavaScriptConfirmDialog is not implemented on the current platform',
+    );
+  }
+
+  /// Sets a callback that notifies the host application that the web page
+  /// wants to display a JavaScript prompt() dialog.
+  Future<void> setOnJavaScriptTextInputDialog(
+      Future<String> Function(JavaScriptTextInputDialogRequest request)
+          onJavaScriptTextInputDialog) async {
+    throw UnimplementedError(
+      'setOnJavaScriptTextInputDialog is not implemented on the current platform',
+    );
+  }
 }
 
 /// Describes the parameters necessary for registering a JavaScript channel.

packages/webview_flutter/webview_flutter_platform_interface/lib/src/types/javascript_dialog_request.dart

@@ -0,0 +1,57 @@
+// 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 'package:flutter/foundation.dart';
+
+/// Defines the parameters that support `PlatformWebViewController.setOnJavaScriptAlertDialog`.
+@immutable
+class JavaScriptAlertDialogRequest {
+  /// Creates a [JavaScriptAlertDialogRequest].
+  const JavaScriptAlertDialogRequest({
+    required this.message,
+    required this.url,
+  });
+
+  /// The message to be displayed in the window.
+  final String message;
+
+  /// The URL of the page requesting the dialog.
+  final String url;
+}
+
+/// Defines the parameters that support `PlatformWebViewController.setOnJavaScriptConfirmDialog`.
+@immutable
+class JavaScriptConfirmDialogRequest {
+  /// Creates a [JavaScriptConfirmDialogRequest].
+  const JavaScriptConfirmDialogRequest({
+    required this.message,
+    required this.url,
+  });
+
+  /// The message to be displayed in the window.
+  final String message;
+
+  /// The URL of the page requesting the dialog.
+  final String url;
+}
+
+/// Defines the parameters that support `PlatformWebViewController.setOnJavaScriptTextInputDialog`.
+@immutable
+class JavaScriptTextInputDialogRequest {
+  /// Creates a [JavaScriptAlertDialogRequest].
+  const JavaScriptTextInputDialogRequest({
+    required this.message,
+    required this.url,
+    required this.defaultText,
+  });
+
+  /// The message to be displayed in the window.
+  final String message;
+
+  /// The URL of the page requesting the dialog.
+  final String url;
+
+  /// The initial text to display in the text entry field.
+  final String? defaultText;
+}

packages/webview_flutter/webview_flutter_platform_interface/lib/src/types/types.dart

@@ -5,6 +5,7 @@
 export 'http_auth_request.dart';
 export 'http_response_error.dart';
 export 'javascript_console_message.dart';
+export 'javascript_dialog_request.dart';
 export 'javascript_log_level.dart';
 export 'javascript_message.dart';
 export 'javascript_mode.dart';

packages/webview_flutter/webview_flutter_platform_interface/pubspec.yaml

@@ -4,7 +4,7 @@ repository: https://github.com/flutter/packages/tree/main/packages/webview_flutt
 issue_tracker: https://github.com/flutter/flutter/issues?q=is%3Aissue+is%3Aopen+label%3A%22p%3A+webview_flutter%22
 # NOTE: We strongly prefer non-breaking changes, even at the expense of a
 # less-clean API. See https://flutter.dev/go/platform-interface-breaking-changes
-version: 2.8.0
+version: 2.9.0
 
 environment:
   sdk: ">=3.0.0 <4.0.0"

packages/webview_flutter/webview_flutter_platform_interface/test/platform_webview_controller_test.dart

@@ -414,6 +414,49 @@ void main() {
       throwsUnimplementedError,
     );
   });
+
+  test(
+      'Default implementation of setOnJavaScriptAlertDialog should throw unimplemented error',
+      () {
+    final PlatformWebViewController controller =
+        ExtendsPlatformWebViewController(
+            const PlatformWebViewControllerCreationParams());
+
+    expect(
+      () => controller.setOnJavaScriptAlertDialog((_) async {}),
+      throwsUnimplementedError,
+    );
+  });
+
+  test(
+      'Default implementation of setOnJavaScriptConfirmDialog should throw unimplemented error',
+      () {
+    final PlatformWebViewController controller =
+        ExtendsPlatformWebViewController(
+            const PlatformWebViewControllerCreationParams());
+
+    expect(
+      () => controller.setOnJavaScriptConfirmDialog((_) async {
+        return false;
+      }),
+      throwsUnimplementedError,
+    );
+  });
+
+  test(
+      'Default implementation of setOnJavaScriptTextInputDialog should throw unimplemented error',
+      () {
+    final PlatformWebViewController controller =
+        ExtendsPlatformWebViewController(
+            const PlatformWebViewControllerCreationParams());
+
+    expect(
+      () => controller.setOnJavaScriptTextInputDialog((_) async {
+        return '';
+      }),
+      throwsUnimplementedError,
+    );
+  });
 }
 
 class MockWebViewPlatformWithMixin extends MockWebViewPlatform