Move DBMessageFilter to content/child since its only used in child ptypes

content/common/db_message_filter.h

-// Copyright (c) 2012 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_COMMON_DB_MESSAGE_FILTER_H_
-#define CONTENT_COMMON_DB_MESSAGE_FILTER_H_
-
-#include "ipc/ipc_channel_proxy.h"
-
-namespace content {
-
-// Receives database messages from the browser process and processes them on the
-// IO thread.
-class DBMessageFilter : public IPC::ChannelProxy::MessageFilter {
- public:
-  DBMessageFilter();
-
-  // IPC::ChannelProxy::MessageFilter
-  virtual bool OnMessageReceived(const IPC::Message& message) OVERRIDE;
-
- protected:
-  virtual ~DBMessageFilter() {}
-
- private:
-  void OnDatabaseUpdateSize(const std::string& origin_identifier,
-                            const 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 string16& database_name);
-};
-
-}  // namespace content
-
-#endif  // CONTENT_COMMON_DB_MESSAGE_FILTER_H_