Expose Service Describer in Dart mojo package

mojo/dart/packages/mojo_services/lib/mojo/terminal/terminal_client.mojom.dart

Index: mojo/dart/packages/mojo_services/lib/mojo/terminal/terminal_client.mojom.dart
diff --git a/mojo/dart/packages/mojo_services/lib/mojo/terminal/terminal_client.mojom.dart b/mojo/dart/packages/mojo_services/lib/mojo/terminal/terminal_client.mojom.dart
index 7db35d40806581882c358df13d3aff88c103cdb6..5d21bcb9fe45eee931db85d6574c9c66b753bf09 100644
--- a/mojo/dart/packages/mojo_services/lib/mojo/terminal/terminal_client.mojom.dart
+++ b/mojo/dart/packages/mojo_services/lib/mojo/terminal/terminal_client.mojom.dart
@@ -92,11 +92,14 @@ const int _TerminalClient_connectToTerminalName = 0;
 
 
 class _TerminalClientServiceDescription 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 TerminalClient {
@@ -267,8 +270,13 @@ class TerminalClientStub extends bindings.Stub {
 
   int get version => 0;
 
-  service_describer.ServiceDescription get serviceDescription =>
-    new _TerminalClientServiceDescription();
+  static service_describer.ServiceDescription _cachedServiceDescription;
+  static service_describer.ServiceDescription get serviceDescription {
+    if (_cachedServiceDescription == null) {
+      _cachedServiceDescription = new _TerminalClientServiceDescription();
+    }
+    return _cachedServiceDescription;
+  }
 }