[AppRemoting] Break out AppRemoting shared module (re-land).

remoting/webapp/app_remoting/js/ar_background.js

 // Copyright 2014 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.
 
 /** @type {chrome.app.window.AppWindow} */
 var mainWindow = null;
 
 /**
  * The main window cannot delete its context menu entries on close because it
  * is being torn down at that point and doesn't have access to the necessary
@@ skipping 37 matching lines @@
 
   /** @param {chrome.app.window.AppWindow} appWindow */
   function onCreate(appWindow) {
     // Set the global window.
     mainWindow = appWindow;
 
     // Clean up the windows sub-menu when the application quits.
     appWindow.onClosed.addListener(onClosed);
   };
 
-  chrome.app.window.create('main.html', windowAttributes, onCreate);
+  // TODO(garykac) Add code to switch between dev and prod shared modules.
+  chrome.app.window.create(
+      '_modules/koejkfhmphamcgafjmkellhnekdkopod/main.html',
+      windowAttributes, onCreate);
 };
 
 /** @param {Event} event */
 function onWindowMessage(event) {
   var method = /** @type {string} */ (event.data['method']);
   var id = /** @type {string} */ (event.data['id']);
   switch (method) {
     case 'addContextMenuId':
       contextMenuIds[id] = true;
       break;
     case 'removeContextMenuId':
       delete contextMenuIds[id];
       break;
   }
 };
 
 chrome.app.runtime.onLaunched.addListener(createWindow);
 window.addEventListener('message', onWindowMessage, false);