Implement a module system for the extension bindings JS.

chrome/renderer/resources/extensions/page_actions_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 pageActions API.
 
 (function() {
 
-native function GetChromeHidden();
-native function GetCurrentPageActions();
+var pageActionsNatives = requireNative('page_actions');
+var GetCurrentPageActions = pageActionsNatives.GetCurrentPageActions;
 
-GetChromeHidden().registerCustomHook('pageActions',
-                                     function(bindingsAPI, extensionId) {
+var chromeHidden = requireNative('chrome_hidden').GetChromeHidden();
+
+chromeHidden.registerCustomHook('pageActions',
+                                function(bindingsAPI, extensionId) {
   var pageActions = GetCurrentPageActions(extensionId);
   var oldStyleEventName = 'pageActions';
   for (var i = 0; i < pageActions.length; ++i) {
     // Setup events for each extension_id/page_action_id string we find.
     chrome.pageActions[pageActions[i]] = new chrome.Event(oldStyleEventName);
   }
 });
 
 })();