Fix (attempt) for crbug.com/459115.

content/browser/message_port_service.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_service.h"
 
 #include "content/common/message_port_messages.h"
 #include "content/public/browser/browser_thread.h"
 #include "content/public/browser/message_port_delegate.h"
 
@@ skipping 45 matching lines @@
 MessagePortService::MessagePortService()
     : next_message_port_id_(0) {
 }
 
 MessagePortService::~MessagePortService() {
 }
 
 void MessagePortService::UpdateMessagePort(int message_port_id,
                                            MessagePortDelegate* delegate,
                                            int routing_id) {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
   if (!message_ports_.count(message_port_id)) {
     NOTREACHED();
     return;
   }
 
   MessagePort& port = message_ports_[message_port_id];
   port.delegate = delegate;
   port.route_id = routing_id;
 }
 
@@ skipping 231 matching lines @@
     // Do the disentanglement (and be paranoid about the other side existing
     // just in case something unusual happened during entanglement).
     if (message_ports_.count(entangled_id)) {
       message_ports_[entangled_id].entangled_message_port_id = MSG_ROUTING_NONE;
     }
   }
   message_ports_.erase(erase_item);
 }
 
 }  // namespace content