Add a content API to create a message channel.

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/browser/message_port_message_filter.h"
 #include "content/common/message_port_messages.h"
 
 namespace content {
@@ skipping 53 matching lines @@
     MessagePorts::iterator cur_item = iter++;
     if (cur_item->second.filter == filter) {
       Erase(cur_item->first);
     }
   }
 }
 
 void MessagePortService::Create(int route_id,
                                 MessagePortMessageFilter* filter,
                                 int* message_port_id) {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
   *message_port_id = ++next_message_port_id_;
 
   MessagePort port;
   port.filter = filter;
   port.route_id = route_id;
   port.message_port_id = *message_port_id;
   port.entangled_message_port_id = MSG_ROUTING_NONE;
   port.queue_messages = false;
   message_ports_[*message_port_id] = port;
 }
@@ skipping 152 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