Move IPC::MessageFilter and router to a separate file

content/renderer/service_worker/embedded_worker_context_message_filter.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 CONTENT_RENDERER_SERVICE_WORKER_EMBEDDED_WORKER_CONTEXT_MESSAGE_FILTER_H_
 #define CONTENT_RENDERER_SERVICE_WORKER_EMBEDDED_WORKER_CONTEXT_MESSAGE_FILTER_H_
 
 #include "content/child/child_message_filter.h"
 
+namespace base {
+class MessageLoopProxy;
+}
+
 namespace content {
 
 class EmbeddedWorkerContextMessageFilter : public ChildMessageFilter {
  public:
   EmbeddedWorkerContextMessageFilter();
 
  protected:
   virtual ~EmbeddedWorkerContextMessageFilter();
 
   // ChildMessageFilter implementation:
   virtual base::TaskRunner* OverrideTaskRunnerForMessage(
       const IPC::Message& msg) OVERRIDE;
   virtual bool OnMessageReceived(const IPC::Message& msg) OVERRIDE;
 
   scoped_refptr<base::MessageLoopProxy> main_thread_loop_proxy_;
   scoped_refptr<ThreadSafeSender> thread_safe_sender_;
 
   DISALLOW_COPY_AND_ASSIGN(EmbeddedWorkerContextMessageFilter);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_RENDERER_SERVICE_WORKER_EMBEDDED_WORKER_CONTEXT_MESSAGE_FILTER_H_