feat: support configure a custom launch url for flutter web (#95002)

packages/flutter_tools/lib/src/commands/run.dart

@@ -228,6 +228,7 @@ abstract class RunCommandBase extends FlutterCommand with DeviceBasedDevelopment
         webRunHeadless: featureFlags.isWebEnabled && boolArg('web-run-headless'),
         webBrowserDebugPort: browserDebugPort,
         webEnableExpressionEvaluation: featureFlags.isWebEnabled && boolArg('web-enable-expression-evaluation'),
+        webLaunchUrl: featureFlags.isWebEnabled ? stringArg('web-launch-url') : null,
         vmserviceOutFile: stringArg('vmservice-out-file'),
         fastStart: argParser.options.containsKey('fast-start')
           && boolArg('fast-start')

packages/flutter_tools/lib/src/device.dart

@@ -763,6 +763,7 @@ class DebuggingOptions {
     this.webRunHeadless = false,
     this.webBrowserDebugPort,
     this.webEnableExpressionEvaluation = false,
+    this.webLaunchUrl,
     this.vmserviceOutFile,
     this.fastStart = false,
     this.nullAssertions = false,
@@ -779,6 +780,7 @@ class DebuggingOptions {
       this.webUseSseForInjectedClient = true,
       this.webRunHeadless = false,
       this.webBrowserDebugPort,
+      this.webLaunchUrl,
       this.cacheSkSL = false,
       this.traceAllowlist,
     }) : debuggingEnabled = false,
@@ -852,6 +854,9 @@ class DebuggingOptions {
   /// Enable expression evaluation for web target.
   final bool webEnableExpressionEvaluation;
 
+  /// Allow developers to customize the browser's launch URL
+  final String? webLaunchUrl;
+
   /// A file where the VM Service URL should be written after the application is started.
   final String? vmserviceOutFile;
   final bool fastStart;

packages/flutter_tools/lib/src/runner/flutter_command.dart

@@ -263,6 +263,10 @@ abstract class FlutterCommand extends Command<void> {
       help: 'Enables expression evaluation in the debugger.',
       hide: !verboseHelp,
     );
+    argParser.addOption('web-launch-url',
+      help: 'The URL to provide to the browser. Defaults to an HTTP URL with the host '
+          'name of "--web-hostname", the port of "--web-port", and the path set to "/".',
+    );
   }
 
   void usesTargetOption() {

packages/flutter_tools/lib/src/web/web_device.dart

@@ -6,6 +6,7 @@ import 'package:meta/meta.dart';
 import 'package:process/process.dart';
 
 import '../application_package.dart';
+import '../base/common.dart';
 import '../base/file_system.dart';
 import '../base/io.dart';
 import '../base/logger.dart';
@@ -128,7 +129,17 @@ abstract class ChromiumDevice extends Device {
   }) async {
     // See [ResidentWebRunner.run] in flutter_tools/lib/src/resident_web_runner.dart
     // for the web initialization and server logic.
-    final String url = platformArgs['uri']! as String;
+    String url;
+    if (debuggingOptions.webLaunchUrl != null) {
+      final RegExp pattern = RegExp(r'^((http)?:\/\/)[^\s]+');
+      if (pattern.hasMatch(debuggingOptions.webLaunchUrl!)) {
+        url = debuggingOptions.webLaunchUrl!;
+      } else {
+        throwToolExit('"${debuggingOptions.webLaunchUrl}" is not a vaild HTTP URL.');
+      }
+    } else {
+      url = platformArgs['uri']! as String;
+    }
     final bool launchChrome = platformArgs['no-launch-chrome'] != true;
     if (launchChrome) {
       _chrome = await chromeLauncher.launch(

packages/flutter_tools/test/commands.shard/hermetic/run_test.dart

@@ -594,6 +594,30 @@ void main() {
     FileSystem: () => MemoryFileSystem.test(),
     ProcessManager: () => FakeProcessManager.any(),
   });
+
+  testUsingContext('fails when "--web-launch-url" is not supported', () async {
+    final RunCommand command = RunCommand();
+    await expectLater(
+          () => createTestCommandRunner(command).run(<String>[
+        'run',
+        '--web-launch-url=http://flutter.dev',
+      ]),
+      throwsA(isException.having(
+            (Exception exception) => exception.toString(),
+        'toString',
+        isNot(contains('web-launch-url')),
+      )),
+    );
+
+    final DebuggingOptions options = await command.createDebuggingOptions(true);
+    expect(options.webLaunchUrl, 'http://flutter.dev');
+
+    final RegExp pattern = RegExp(r'^((http)?:\/\/)[^\s]+');
+    expect(pattern.hasMatch(options.webLaunchUrl), true);
+  }, overrides: <Type, Generator>{
+    ProcessManager: () => FakeProcessManager.any(),
+    Logger: () => BufferLogger.test(),
+  });
 }
 
 class FakeDeviceManager extends Fake implements DeviceManager {