Expose Service Describer in Dart mojo package

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

Index: mojo/dart/packages/mojo_services/lib/sensors/sensors.mojom.dart
diff --git a/mojo/dart/packages/mojo_services/lib/sensors/sensors.mojom.dart b/mojo/dart/packages/mojo_services/lib/sensors/sensors.mojom.dart
index 7c3a83ace95a3c04dcbcdaf5c0d218e87add213a..0c71e64fe354622e38f779c33b03f96dd6f39389 100644
--- a/mojo/dart/packages/mojo_services/lib/sensors/sensors.mojom.dart
+++ b/mojo/dart/packages/mojo_services/lib/sensors/sensors.mojom.dart
@@ -533,11 +533,14 @@ const int _SensorListener_onSensorChangedName = 1;
 
 
 class _SensorListenerServiceDescription 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 SensorListener {
@@ -723,8 +726,13 @@ class SensorListenerStub extends bindings.Stub {
 
   int get version => 0;
 
-  service_describer.ServiceDescription get serviceDescription =>
-    new _SensorListenerServiceDescription();
+  static service_describer.ServiceDescription _cachedServiceDescription;
+  static service_describer.ServiceDescription get serviceDescription {
+    if (_cachedServiceDescription == null) {
+      _cachedServiceDescription = new _SensorListenerServiceDescription();
+    }
+    return _cachedServiceDescription;
+  }
 }
 
 const int _SensorService_addListenerName = 0;
@@ -732,11 +740,14 @@ const int _SensorService_addListenerName = 0;
 
 
 class _SensorServiceServiceDescription 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 SensorService {
@@ -908,8 +919,13 @@ class SensorServiceStub extends bindings.Stub {
 
   int get version => 0;
 
-  service_describer.ServiceDescription get serviceDescription =>
-    new _SensorServiceServiceDescription();
+  static service_describer.ServiceDescription _cachedServiceDescription;
+  static service_describer.ServiceDescription get serviceDescription {
+    if (_cachedServiceDescription == null) {
+      _cachedServiceDescription = new _SensorServiceServiceDescription();
+    }
+    return _cachedServiceDescription;
+  }
 }