Implement a module system for the extension bindings JS.

chrome/renderer/resources/extensions/tts_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 tts API.
 
-(function() {
+var ttsNatives = requireNative('tts');
+var GetNextTTSEventId = ttsNatives.GetNextTTSEventId;
 
-native function GetChromeHidden();
-native function GetNextTTSEventId();
-
-var chromeHidden = GetChromeHidden();
+var chromeHidden = requireNative('chrome_hidden').GetChromeHidden();
 
 chromeHidden.registerCustomHook('tts', function(api) {
   var apiFunctions = api.apiFunctions;
   var sendRequest = api.sendRequest;
 
   chromeHidden.tts = {};
   chromeHidden.tts.handlers = {};
   chrome.tts.onEvent.addListener(function(event) {
     var eventHandler = chromeHidden.tts.handlers[event.srcId];
     if (eventHandler) {
@@ skipping 12 matching lines @@
     var args = arguments;
     if (args.length > 1 && args[1] && args[1].onEvent) {
       var id = GetNextTTSEventId();
       args[1].srcId = id;
       chromeHidden.tts.handlers[id] = args[1].onEvent;
     }
     sendRequest(this.name, args, this.definition.parameters);
     return id;
   });
 });
-
-})();