Implement a module system for the extension bindings JS.

chrome/renderer/resources/extensions/chrome_private_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 chromePrivate API.
 
-(function() {
+var chromePrivate = requireNative('chrome_private');
+var DecodeJPEG = chromePrivate.DecodeJPEG;
 
-native function GetChromeHidden();
-native function DecodeJPEG(jpegImage);
+var chromeHidden = requireNative('chrome_hidden').GetChromeHidden();
 
-GetChromeHidden().registerCustomHook('chromePrivate', function(bindingsAPI) {
+chromeHidden.registerCustomHook('chromePrivate', function(bindingsAPI) {
   var apiFunctions = bindingsAPI.apiFunctions;
 
   apiFunctions.setHandleRequest('decodeJPEG', function(jpeg_image) {
     return DecodeJPEG(jpeg_image);
   });
 });
-
-})();