A recent change (r64277) added an extra argument to Port.dispatchOnDisconnect...

chrome/browser/automation/extension_port_container.cc

 // Copyright (c) 2010 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 "chrome/browser/automation/extension_port_container.h"
 
 #include "base/logging.h"
 #include "base/json/json_reader.h"
 #include "base/json/json_writer.h"
 #include "base/values.h"
@@ skipping 101 matching lines @@
     const ListValue& args,
     const GURL& event_url) {
   if (function_name == ExtensionMessageService::kDispatchOnMessage) {
     DCHECK_EQ(args.GetSize(), 2u);
 
     std::string message;
     int source_port_id;
     if (args.GetString(0, &message) && args.GetInteger(1, &source_port_id))
       OnExtensionHandleMessage(message, source_port_id);
   } else if (function_name == ExtensionMessageService::kDispatchOnDisconnect) {
-    DCHECK_EQ(args.GetSize(), 1u);
+    DCHECK_EQ(args.GetSize(), 2u);
     int port_id;
     if (args.GetInteger(0, &port_id))
       OnExtensionPortDisconnected(port_id);
   } else if (function_name == ExtensionMessageService::kDispatchOnConnect) {
     // Do nothing.
     // TODO(siggi): implement
   } else {
     NOTREACHED() << function_name << " shouldn't be called.";
   }
 }
@@ skipping 119 matching lines @@
       // This will delete the port and notify the other end of the disconnect.
       automation->RemovePortContainer(port);
     }
   } else {
     // We don't expect other messages here.
     NOTREACHED();
   }
 
   return true;
 }