Expose Service Describer in Dart mojo package

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

Index: mojo/dart/packages/mojo_services/lib/mojo/geocoder.mojom.dart
diff --git a/mojo/dart/packages/mojo_services/lib/mojo/geocoder.mojom.dart b/mojo/dart/packages/mojo_services/lib/mojo/geocoder.mojom.dart
index 8d8a42f77b55d679b147b4e7120440dbe32df182..75ff9c8424bee4cd06af4ab00cb20991fac2d1ee 100644
--- a/mojo/dart/packages/mojo_services/lib/mojo/geocoder.mojom.dart
+++ b/mojo/dart/packages/mojo_services/lib/mojo/geocoder.mojom.dart
@@ -1116,11 +1116,14 @@ const int _Geocoder_locationToAddressName = 1;
 
 
 class _GeocoderServiceDescription 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 Geocoder {
@@ -1394,8 +1397,13 @@ class GeocoderStub extends bindings.Stub {
 
   int get version => 0;
 
-  service_describer.ServiceDescription get serviceDescription =>
-    new _GeocoderServiceDescription();
+  static service_describer.ServiceDescription _cachedServiceDescription;
+  static service_describer.ServiceDescription get serviceDescription {
+    if (_cachedServiceDescription == null) {
+      _cachedServiceDescription = new _GeocoderServiceDescription();
+    }
+    return _cachedServiceDescription;
+  }
 }