Expose Service Describer in Dart mojo package

mojo/dart/packages/mojo_services/lib/mojo/media/media_sink.mojom.dart

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 library media_sink_mojom;
 
 import 'dart:async';
 
 import 'package:mojo/bindings.dart' as bindings;
 import 'package:mojo/core.dart' as core;
@@ skipping 745 matching lines @@
 const int _MediaSink_getMasterClockName = 1;
 const int _MediaSink_setMasterClockName = 2;
 const int _MediaSink_getConsumerName = 3;
 const int _MediaSink_getStatusName = 4;
 const int _MediaSink_playName = 5;
 const int _MediaSink_pauseName = 6;
 
 
 
 class _MediaSinkServiceDescription implements service_describer.ServiceDescription {
-  dynamic getTopLevelInterface([Function responseFactory]) => null;
+  dynamic getTopLevelInterface([Function responseFactory]) =>
+      responseFactory(null);
 
-  dynamic getTypeDefinition(String typeKey, [Function responseFactory]) => null;
+  dynamic getTypeDefinition(String typeKey, [Function responseFactory]) =>
+      responseFactory(null);
 
-  dynamic getAllTypeDefinitions([Function responseFactory]) => null;
+  dynamic getAllTypeDefinitions([Function responseFactory]) =>
+      responseFactory(null);
 }
 
 abstract class MediaSink {
   static const String serviceName = null;
   dynamic getClockDisposition([Function responseFactory = null]);
   void getMasterClock(Object masterClock);
   void setMasterClock(Object masterClock);
   void getConsumer(Object consumer);
   dynamic getStatus(int versionLastSeen,[Function responseFactory = null]);
   void play();
@@ skipping 322 matching lines @@
     _impl = d;
   }
 
   String toString() {
     var superString = super.toString();
     return "MediaSinkStub($superString)";
   }
 
   int get version => 0;
 
-  service_describer.ServiceDescription get serviceDescription =>
+  static service_describer.ServiceDescription get serviceDescription =>
     new _MediaSinkServiceDescription();
 }