[mojo] Add Mojo bindings support for IPC::ParamTraits

mojo/public/cpp/bindings/interface_request.h

Index: mojo/public/cpp/bindings/interface_request.h
diff --git a/mojo/public/cpp/bindings/interface_request.h b/mojo/public/cpp/bindings/interface_request.h
index c139306e2c8d671871c039d3960e5178bc7e546d..22ba015ff7b1d81988bea0e7f003b7d9957f94b6 100644
--- a/mojo/public/cpp/bindings/interface_request.h
+++ b/mojo/public/cpp/bindings/interface_request.h
@@ -107,10 +107,12 @@ InterfaceRequest<Interface> MakeRequest(ScopedMessagePipeHandle handle) {
 //   CreateSource(source_request.Pass());  // Create implementation locally.
 //
 template <typename Interface>
-InterfaceRequest<Interface> GetProxy(InterfacePtr<Interface>* ptr) {
+InterfaceRequest<typename Interface::GenericInterface_>
+GetProxy(InterfacePtr<Interface>* ptr) {
   MessagePipe pipe;
   ptr->Bind(InterfacePtrInfo<Interface>(pipe.handle0.Pass(), 0u));
-  return MakeRequest<Interface>(pipe.handle1.Pass());
+  return MakeRequest<typename Interface::GenericInterface_>(
+      pipe.handle1.Pass());
 }
 
 }  // namespace mojo