Move a bunch of content\common code into the content namespace.

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 string16& origin_identifier,
                             const string16& database_name,
                             int64 database_size);
   void OnDatabaseUpdateSpaceAvailable(const string16& origin_identifier,
                                       int64 space_available);
   void OnDatabaseResetSpaceAvailable(const string16& origin_identifier);
   void OnDatabaseCloseImmediately(const string16& origin_identifier,
                                   const string16& database_name);
 };
 
+}  // namespace content
+
 #endif  // CONTENT_COMMON_DB_MESSAGE_FILTER_H_