Moves around mojo js bindings code

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"
-#include "mojo/public/system/async_waiter.h"
-
-namespace mojo {
-namespace js {
-
-class WaitingCallback : public gin::Wrappable<WaitingCallback> {
- public:
-  static gin::WrapperInfo kWrapperInfo;
-
-  static gin::Handle<WaitingCallback> Create(
-      v8::Isolate* isolate, v8::Handle<v8::Function> callback);
-
-  MojoAsyncWaitID wait_id() const {
-    return wait_id_;
-  }
-
-  void set_wait_id(MojoAsyncWaitID wait_id) {
-    wait_id_ = wait_id;
-  }
-
-  // MojoAsyncWaitCallback
-  static void CallOnHandleReady(void* closure, MojoResult result);
-
- private:
-  WaitingCallback(v8::Isolate* isolate, v8::Handle<v8::Function> callback);
-  virtual ~WaitingCallback();
-
-  void OnHandleReady(MojoResult result);
-
-  base::WeakPtr<gin::Runner> runner_;
-  MojoAsyncWaitID wait_id_;
-
-  DISALLOW_COPY_AND_ASSIGN(WaitingCallback);
-};
-
-}  // namespace js
-}  // namespace mojo
-
-#endif  // MOJO_APPS_JS_BINDINGS_WAITING_CALLBACK_H_