Expose Service Describer in Dart mojo package

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

Index: mojo/dart/packages/mojo_services/lib/http_server/http_server.mojom.dart
diff --git a/mojo/dart/packages/mojo_services/lib/http_server/http_server.mojom.dart b/mojo/dart/packages/mojo_services/lib/http_server/http_server.mojom.dart
index a1d816a2791b6676f7c61a97c887916e7e4dd109..387f74b95535b7a9a20c835d39a31d8e4c1f15c0 100644
--- a/mojo/dart/packages/mojo_services/lib/http_server/http_server.mojom.dart
+++ b/mojo/dart/packages/mojo_services/lib/http_server/http_server.mojom.dart
@@ -463,11 +463,14 @@ const int _HttpServer_getPortName = 1;
 
 
 class _HttpServerServiceDescription 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 HttpServer {
@@ -737,8 +740,13 @@ class HttpServerStub extends bindings.Stub {
 
   int get version => 0;
 
-  service_describer.ServiceDescription get serviceDescription =>
-    new _HttpServerServiceDescription();
+  static service_describer.ServiceDescription _cachedServiceDescription;
+  static service_describer.ServiceDescription get serviceDescription {
+    if (_cachedServiceDescription == null) {
+      _cachedServiceDescription = new _HttpServerServiceDescription();
+    }
+    return _cachedServiceDescription;
+  }
 }
 
 const int _HttpHandler_handleRequestName = 0;
@@ -746,11 +754,14 @@ const int _HttpHandler_handleRequestName = 0;
 
 
 class _HttpHandlerServiceDescription 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 HttpHandler {
@@ -963,8 +974,13 @@ class HttpHandlerStub extends bindings.Stub {
 
   int get version => 0;
 
-  service_describer.ServiceDescription get serviceDescription =>
-    new _HttpHandlerServiceDescription();
+  static service_describer.ServiceDescription _cachedServiceDescription;
+  static service_describer.ServiceDescription get serviceDescription {
+    if (_cachedServiceDescription == null) {
+      _cachedServiceDescription = new _HttpHandlerServiceDescription();
+    }
+    return _cachedServiceDescription;
+  }
 }