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();
-native function OpenChannelToExtension(sourceId, targetId, name);
+var extension = requireNative('extension');
+var GetExtensionViews = extension.GetExtensionViews;
+var OpenChannelToExtension = extension.OpenChannelToExtension;
 
-var chromeHidden = GetChromeHidden();
+var chromeHidden = requireNative('chrome_hidden').GetChromeHidden();
 
 // 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;
 
 chromeHidden.registerCustomHook('extension',
                                 function(bindingsAPI, extensionId) {
@@ skipping 119 matching lines @@
       name = connectInfo.name;
 
     var portId = OpenChannelToExtension(extensionId, targetId, name);
     if (portId >= 0)
       return chromeHidden.Port.createPort(portId, name);
     throw new Error("Error connecting to extension '" + targetId + "'");
   });
 });
 
 })();