Revert "Allow MessageFilters to restrict listening to specific message classes"

content/browser/message_port_message_filter.cc

 // 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.
 
 #include "content/browser/message_port_message_filter.h"
 
 #include "content/browser/message_port_service.h"
 #include "content/common/message_port_messages.h"
 
 namespace content {
 
 MessagePortMessageFilter::MessagePortMessageFilter(
     const NextRoutingIDCallback& callback)
-    : BrowserMessageFilter(MessagePortMsgStart),
-      next_routing_id_(callback) {
+    : next_routing_id_(callback) {
 }
 
 MessagePortMessageFilter::~MessagePortMessageFilter() {
 }
 
 void MessagePortMessageFilter::OnChannelClosing() {
   MessagePortService::GetInstance()->OnMessagePortMessageFilterClosing(this);
 }
 
 bool MessagePortMessageFilter::OnMessageReceived(const IPC::Message& message,
@@ skipping 31 matching lines @@
   return next_routing_id_.Run();
 }
 
 void MessagePortMessageFilter::OnCreateMessagePort(int *route_id,
                                                    int* message_port_id) {
   *route_id = next_routing_id_.Run();
   MessagePortService::GetInstance()->Create(*route_id, this, message_port_id);
 }
 
 }  // namespace content