Expose Service Describer in Dart mojo package

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

Index: mojo/dart/packages/mojo_services/lib/mojo/asset_bundle/asset_bundle.mojom.dart
diff --git a/mojo/dart/packages/mojo_services/lib/mojo/asset_bundle/asset_bundle.mojom.dart b/mojo/dart/packages/mojo_services/lib/mojo/asset_bundle/asset_bundle.mojom.dart
index ee2b4baf472a11c349cd171fbac4780a232fcbf1..6b28869ae7647e90167f71d9c714d47eef7c531d 100644
--- a/mojo/dart/packages/mojo_services/lib/mojo/asset_bundle/asset_bundle.mojom.dart
+++ b/mojo/dart/packages/mojo_services/lib/mojo/asset_bundle/asset_bundle.mojom.dart
@@ -251,11 +251,14 @@ const int _AssetBundle_getAsStreamName = 0;
 
 
 class _AssetBundleServiceDescription 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 AssetBundle {
@@ -468,8 +471,13 @@ class AssetBundleStub extends bindings.Stub {
 
   int get version => 0;
 
-  service_describer.ServiceDescription get serviceDescription =>
-    new _AssetBundleServiceDescription();
+  static service_describer.ServiceDescription _cachedServiceDescription;
+  static service_describer.ServiceDescription get serviceDescription {
+    if (_cachedServiceDescription == null) {
+      _cachedServiceDescription = new _AssetBundleServiceDescription();
+    }
+    return _cachedServiceDescription;
+  }
 }
 
 const int _AssetUnpacker_unpackZipStreamName = 0;
@@ -477,11 +485,14 @@ const int _AssetUnpacker_unpackZipStreamName = 0;
 
 
 class _AssetUnpackerServiceDescription 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 AssetUnpacker {
@@ -653,8 +664,13 @@ class AssetUnpackerStub extends bindings.Stub {
 
   int get version => 0;
 
-  service_describer.ServiceDescription get serviceDescription =>
-    new _AssetUnpackerServiceDescription();
+  static service_describer.ServiceDescription _cachedServiceDescription;
+  static service_describer.ServiceDescription get serviceDescription {
+    if (_cachedServiceDescription == null) {
+      _cachedServiceDescription = new _AssetUnpackerServiceDescription();
+    }
+    return _cachedServiceDescription;
+  }
 }