Expose Service Describer in Dart mojo package

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

Index: mojo/dart/packages/mojo_services/lib/activity/activity.mojom.dart
diff --git a/mojo/dart/packages/mojo_services/lib/activity/activity.mojom.dart b/mojo/dart/packages/mojo_services/lib/activity/activity.mojom.dart
index 744e9171e14513e3143d30f0f6ae451bdedca2ad..9eff8b57c326ae15b2bad07294a990280a550f0f 100644
--- a/mojo/dart/packages/mojo_services/lib/activity/activity.mojom.dart
+++ b/mojo/dart/packages/mojo_services/lib/activity/activity.mojom.dart
@@ -1719,11 +1719,14 @@ const int _Activity_setRequestedOrientationName = 5;
 
 
 class _ActivityServiceDescription 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 Activity {
@@ -1968,8 +1971,13 @@ class ActivityStub extends bindings.Stub {
 
   int get version => 0;
 
-  service_describer.ServiceDescription get serviceDescription =>
-    new _ActivityServiceDescription();
+  static service_describer.ServiceDescription _cachedServiceDescription;
+  static service_describer.ServiceDescription get serviceDescription {
+    if (_cachedServiceDescription == null) {
+      _cachedServiceDescription = new _ActivityServiceDescription();
+    }
+    return _cachedServiceDescription;
+  }
 }
 
 const int _PathService_getAppDataDirName = 0;
@@ -1979,11 +1987,14 @@ const int _PathService_getCacheDirName = 2;
 
 
 class _PathServiceServiceDescription 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 PathService {
@@ -2307,8 +2318,13 @@ class PathServiceStub extends bindings.Stub {
 
   int get version => 0;
 
-  service_describer.ServiceDescription get serviceDescription =>
-    new _PathServiceServiceDescription();
+  static service_describer.ServiceDescription _cachedServiceDescription;
+  static service_describer.ServiceDescription get serviceDescription {
+    if (_cachedServiceDescription == null) {
+      _cachedServiceDescription = new _PathServiceServiceDescription();
+    }
+    return _cachedServiceDescription;
+  }
 }
 
 const int _UserFeedback_performHapticFeedbackName = 0;
@@ -2317,11 +2333,14 @@ const int _UserFeedback_performAuralFeedbackName = 1;
 
 
 class _UserFeedbackServiceDescription 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 UserFeedback {
@@ -2507,8 +2526,13 @@ class UserFeedbackStub extends bindings.Stub {
 
   int get version => 0;
 
-  service_describer.ServiceDescription get serviceDescription =>
-    new _UserFeedbackServiceDescription();
+  static service_describer.ServiceDescription _cachedServiceDescription;
+  static service_describer.ServiceDescription get serviceDescription {
+    if (_cachedServiceDescription == null) {
+      _cachedServiceDescription = new _UserFeedbackServiceDescription();
+    }
+    return _cachedServiceDescription;
+  }
 }