Expose Service Describer in Dart mojo package

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

Index: mojo/dart/packages/mojo_services/lib/mojo/camera.mojom.dart
diff --git a/mojo/dart/packages/mojo_services/lib/mojo/camera.mojom.dart b/mojo/dart/packages/mojo_services/lib/mojo/camera.mojom.dart
index 0f125651f22fce0d938cfa95d3c9f85e25167aed..6f97576b18426384a2ac935eac0d8eaea33074d9 100644
--- a/mojo/dart/packages/mojo_services/lib/mojo/camera.mojom.dart
+++ b/mojo/dart/packages/mojo_services/lib/mojo/camera.mojom.dart
@@ -581,11 +581,14 @@ const int _CameraRollService_getPhotoName = 2;
 
 
 class _CameraRollServiceServiceDescription 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 CameraRollService {
@@ -868,8 +871,13 @@ class CameraRollServiceStub extends bindings.Stub {
 
   int get version => 0;
 
-  service_describer.ServiceDescription get serviceDescription =>
-    new _CameraRollServiceServiceDescription();
+  static service_describer.ServiceDescription _cachedServiceDescription;
+  static service_describer.ServiceDescription get serviceDescription {
+    if (_cachedServiceDescription == null) {
+      _cachedServiceDescription = new _CameraRollServiceServiceDescription();
+    }
+    return _cachedServiceDescription;
+  }
 }
 
 const int _CameraService_getLatestFrameName = 0;
@@ -877,11 +885,14 @@ const int _CameraService_getLatestFrameName = 0;
 
 
 class _CameraServiceServiceDescription 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 CameraService {
@@ -1093,8 +1104,13 @@ class CameraServiceStub extends bindings.Stub {
 
   int get version => 0;
 
-  service_describer.ServiceDescription get serviceDescription =>
-    new _CameraServiceServiceDescription();
+  static service_describer.ServiceDescription _cachedServiceDescription;
+  static service_describer.ServiceDescription get serviceDescription {
+    if (_cachedServiceDescription == null) {
+      _cachedServiceDescription = new _CameraServiceServiceDescription();
+    }
+    return _cachedServiceDescription;
+  }
 }