[Extensions] Don't allow built-in extensions code to be overridden

extensions/renderer/resources/messaging_utils.js

 // Copyright 2014 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.
 
 // Routines used to normalize arguments to messaging functions.
 
 function alignSendMessageArguments(args, hasOptionsArgument) {
   // Align missing (optional) function arguments with the arguments that
   // schema validation is expecting, e.g.
   //   extension.sendRequest(req)     -> extension.sendRequest(null, req)
@@ skipping 32 matching lines @@
   if (lastArg >= 0)
     targetId = args[lastArg--];
 
   if (lastArg != -1)
     return null;
   if (hasOptionsArgument)
     return [targetId, request, options, responseCallback];
   return [targetId, request, responseCallback];
 }
 
-exports.alignSendMessageArguments = alignSendMessageArguments;
+exports.$set('alignSendMessageArguments', alignSendMessageArguments);