Move IPC::MessageFilter and router to a separate file

content/child/db_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_CHILD_DB_MESSAGE_FILTER_H_
 #define CONTENT_CHILD_DB_MESSAGE_FILTER_H_
 
-#include "ipc/ipc_channel_proxy.h"
+#include "base/strings/string16.h"
+#include "ipc/message_filter.h"
 
 namespace content {
 
 // Receives database messages from the browser process and processes them on the
 // IO thread.
-class DBMessageFilter : public IPC::ChannelProxy::MessageFilter {
+class DBMessageFilter : public IPC::MessageFilter {
  public:
   DBMessageFilter();
 
-  // IPC::ChannelProxy::MessageFilter
+  // IPC::MessageFilter
   virtual bool OnMessageReceived(const IPC::Message& message) OVERRIDE;
 
  protected:
   virtual ~DBMessageFilter() {}
 
  private:
   void OnDatabaseUpdateSize(const std::string& origin_identifier,
                             const base::string16& database_name,
                             int64 database_size);
   void OnDatabaseUpdateSpaceAvailable(const std::string& origin_identifier,
                                       int64 space_available);
   void OnDatabaseResetSpaceAvailable(const std::string& origin_identifier);
   void OnDatabaseCloseImmediately(const std::string& origin_identifier,
                                   const base::string16& database_name);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_CHILD_DB_MESSAGE_FILTER_H_