Expose Service Describer in Dart mojo package

mojo/dart/packages/mojo_services/lib/mojo/clipboard.mojom.dart

Index: mojo/dart/packages/mojo_services/lib/mojo/clipboard.mojom.dart
diff --git a/mojo/dart/packages/mojo_services/lib/mojo/clipboard.mojom.dart b/mojo/dart/packages/mojo_services/lib/mojo/clipboard.mojom.dart
index 3efb1695e35dd52f363bcb1cfaa154efe5447de4..077bfac98f2974e0f936897e388500f435ebfd75 100644
--- a/mojo/dart/packages/mojo_services/lib/mojo/clipboard.mojom.dart
+++ b/mojo/dart/packages/mojo_services/lib/mojo/clipboard.mojom.dart
@@ -713,11 +713,14 @@ class ClipboardType extends bindings.MojoEnum {
 
 
 class _ClipboardServiceDescription 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 Clipboard {
@@ -1064,7 +1067,7 @@ class ClipboardStub extends bindings.Stub {
 
   int get version => 0;
 
-  service_describer.ServiceDescription get serviceDescription =>
+  static service_describer.ServiceDescription get serviceDescription =>
     new _ClipboardServiceDescription();
 }