test(mobile): mock wakelock binary transport for video regression checks

mobile/test/providers/asset_viewer/video_player_ready_test.dart

@@ -10,17 +10,14 @@ class _PlaybackInfo extends Mock implements PlaybackInfo {}
 
 void main() {
   TestWidgetsFlutterBinding.ensureInitialized();
-  const wakelock = BasicMessageChannel<Object?>(
-    'dev.flutter.pigeon.wakelock_plus_platform_interface.WakelockPlusApi.toggle',
-    StandardMessageCodec(),
-  );
+  const wakelock = 'dev.flutter.pigeon.wakelock_plus_platform_interface.WakelockPlusApi.toggle';
   late _Controller controller;
   late VideoPlayerNotifier notifier;
 
   setUp(() {
-    TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger.setMockDecodedMessageHandler<Object?>(
+    TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger.setMockMessageHandler(
       wakelock,
-      (_) async => <Object?>[null],
+      (_) async => const StandardMessageCodec().encodeMessage(<Object?>[null]),
     );
     final playback = _PlaybackInfo();
     when(() => playback.status).thenReturn(PlaybackStatus.stopped);
@@ -35,10 +32,7 @@ void main() {
   tearDown(() async {
     notifier.dispose();
     await Future<void>.delayed(Duration.zero);
-    TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger.setMockDecodedMessageHandler<Object?>(
-      wakelock,
-      null,
-    );
+    TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger.setMockMessageHandler(wakelock, null);
   });
 
   test('newly loaded stopped video offers playback', () {