Implement a module system for the extension bindings JS.

chrome/renderer/resources/extensions/file_browser_handler_custom_bindings.js

 // Copyright (c) 2012 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.
 
 // Custom bindings for the fileBrowserHandler API.
 
-(function() {
+var fileBrowserNatives = requireNative('file_browser_handler');
+var GetExternalFileEntry = fileBrowserNatives.GetExternalFileEntry;
 
-native function GetChromeHidden();
-native function GetExternalFileEntry();
+var chromeHidden = requireNative('chrome_hidden').GetChromeHidden();
 
-var chromeHidden = GetChromeHidden();
 chromeHidden.Event.registerArgumentMassager('fileBrowserHandler.onExecute',
     function(args) {
   if (args.length < 2)
     return;
   var fileList = args[1].entries;
   if (!fileList)
     return;
   // The second parameter for this event's payload is file definition
   // dictionary that we used to reconstruct File API's Entry instance
   // here.
   for (var i = 0; i < fileList.length; i++)
     fileList[i] = GetExternalFileEntry(fileList[i]);
 });
-
-})();