Move IPC::MessageFilter and router to a separate file

ppapi/proxy/plugin_message_filter.cc

 // Copyright (c) 2011 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.
 
 #include "ppapi/proxy/plugin_message_filter.h"
 
 #include "base/bind.h"
 #include "base/logging.h"
+#include "ipc/ipc_channel.h"
 #include "ppapi/proxy/ppapi_messages.h"
 #include "ppapi/proxy/resource_message_params.h"
 #include "ppapi/proxy/resource_reply_thread_registrar.h"
 #include "ppapi/shared_impl/ppapi_globals.h"
 #include "ppapi/shared_impl/proxy_lock.h"
 #include "ppapi/shared_impl/resource.h"
 #include "ppapi/shared_impl/resource_tracker.h"
 
 namespace ppapi {
 namespace proxy {
@@ skipping 82 matching lines @@
     DVLOG_IF(1, reply_params.sequence() != 0)
         << "Pepper resource reply message received but the resource doesn't "
            "exist (probably has been destroyed).";
     return;
   }
   resource->OnReplyReceived(reply_params, nested_msg);
 }
 
 }  // namespace proxy
 }  // namespace ppapi