Gin: Consolidate all the Converter<Wrappable> subclasses.

mojo/apps/js/bindings/waiting_callback.h

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef MOJO_APPS_JS_BINDINGS_WAITING_CALLBACK_H_
 #define MOJO_APPS_JS_BINDINGS_WAITING_CALLBACK_H_
 
 #include "gin/handle.h"
 #include "gin/runner.h"
 #include "gin/wrappable.h"
@@ skipping 28 matching lines @@
 
   base::WeakPtr<gin::Runner> runner_;
   BindingsSupport::AsyncWaitID wait_id_;
 
   DISALLOW_COPY_AND_ASSIGN(WaitingCallback);
 };
 
 }  // namespace js
 }  // namespace mojo
 
-namespace gin {
-
-template<>
-struct Converter<mojo::js::WaitingCallback*>
-    : public WrappableConverter<mojo::js::WaitingCallback> {};
-
-} // namespace gin
-
 #endif  // MOJO_APPS_JS_BINDINGS_WAITING_CALLBACK_H_