support for external download managers

packages/flutter_mozilla_components/lib/src/domain/services/gecko_engine_settings.dart

@@ -148,4 +148,14 @@ class GeckoEngineSettingsService {
   Future<AppLinksMode> getAppLinksMode() {
     return _api.getAppLinksMode();
   }
+
+  /// Sets whether to use external download managers for downloads.
+  /// When enabled, downloads are forwarded to third-party apps like ADM, 1DM, AB DM.
+  Future<void> setUseExternalDownloadManager(bool enabled) {
+    return _api.setUseExternalDownloadManager(enabled);
+  }
+
+  Future<bool> getUseExternalDownloadManager() {
+    return _api.getUseExternalDownloadManager();
+  }
 }

packages/flutter_mozilla_components/lib/src/pigeons/gecko.g.dart

@@ -4481,6 +4481,57 @@ class GeckoEngineSettingsApi {
       return (pigeonVar_replyList[0] as AppLinksMode?)!;
     }
   }
+
+  /// Sets whether to use external download managers for downloads.
+  /// When enabled, downloads are forwarded to third-party apps like ADM, 1DM, AB DM.
+  Future<void> setUseExternalDownloadManager(bool enabled) async {
+    final pigeonVar_channelName = 'dev.flutter.pigeon.flutter_mozilla_components.GeckoEngineSettingsApi.setUseExternalDownloadManager$pigeonVar_messageChannelSuffix';
+    final pigeonVar_channel = BasicMessageChannel<Object?>(
+      pigeonVar_channelName,
+      pigeonChannelCodec,
+      binaryMessenger: pigeonVar_binaryMessenger,
+    );
+    final Future<Object?> pigeonVar_sendFuture = pigeonVar_channel.send(<Object?>[enabled]);
+    final pigeonVar_replyList = await pigeonVar_sendFuture as List<Object?>?;
+    if (pigeonVar_replyList == null) {
+      throw _createConnectionError(pigeonVar_channelName);
+    } else if (pigeonVar_replyList.length > 1) {
+      throw PlatformException(
+        code: pigeonVar_replyList[0]! as String,
+        message: pigeonVar_replyList[1] as String?,
+        details: pigeonVar_replyList[2],
+      );
+    } else {
+      return;
+    }
+  }
+
+  Future<bool> getUseExternalDownloadManager() async {
+    final pigeonVar_channelName = 'dev.flutter.pigeon.flutter_mozilla_components.GeckoEngineSettingsApi.getUseExternalDownloadManager$pigeonVar_messageChannelSuffix';
+    final pigeonVar_channel = BasicMessageChannel<Object?>(
+      pigeonVar_channelName,
+      pigeonChannelCodec,
+      binaryMessenger: pigeonVar_binaryMessenger,
+    );
+    final Future<Object?> pigeonVar_sendFuture = pigeonVar_channel.send(null);
+    final pigeonVar_replyList = await pigeonVar_sendFuture as List<Object?>?;
+    if (pigeonVar_replyList == null) {
+      throw _createConnectionError(pigeonVar_channelName);
+    } else if (pigeonVar_replyList.length > 1) {
+      throw PlatformException(
+        code: pigeonVar_replyList[0]! as String,
+        message: pigeonVar_replyList[1] as String?,
+        details: pigeonVar_replyList[2],
+      );
+    } else if (pigeonVar_replyList[0] == null) {
+      throw PlatformException(
+        code: 'null-error',
+        message: 'Host platform returned null value for non-null return value.',
+      );
+    } else {
+      return (pigeonVar_replyList[0] as bool?)!;
+    }
+  }
 }
 
 class GeckoSessionApi {