Implement a module system for the extension bindings JS.

chrome/renderer/resources/extensions/extension_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 extension API.
 
-(function() {
-
-native function GetChromeHidden();
-native function GetExtensionViews();
+var GetChromeHidden = natives.GetChromeHidden;
+var GetExtensionViews = natives.GetExtensionViews;
 
 // This should match chrome.windows.WINDOW_ID_NONE.
 //
 // We can't use chrome.windows.WINDOW_ID_NONE directly because the
 // chrome.windows API won't exist unless this extension has permission for it;
 // which may not be the case.
 var WINDOW_ID_NONE = -1;
 
 GetChromeHidden().registerCustomHook('extension', function(bindingsAPI) {
   // getTabContentses is retained for backwards compatibility.
@@ skipping 21 matching lines @@
     return GetExtensionViews(-1, "BACKGROUND")[0] || null;
   });
 
   apiFunctions.setHandleRequest("extension.getExtensionTabs",
       function(windowId) {
     if (typeof(windowId) == "undefined")
       windowId = WINDOW_ID_NONE;
     return GetExtensionViews(windowId, "TAB");
   });
 });
-
-})();