Get extension version synchrously from the manifest.

remoting/webapp/jscompiler_hacks.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.
 
 // This file contains various hacks needed to inform JSCompiler of various
 // WebKit- and Chrome-specific properties and methods. It is used only with
 // JSCompiler to verify the type-correctness of our code.
 
 /** @type {HTMLElement} */
 Document.prototype.activeElement;
@@ skipping 92 matching lines @@
    */
   getAuthToken: function(parameters, callback) {}
 };
 
 /** @type {Object} */
 chrome.runtime = {
   /** @type {Object} */
   lastError: {
     /** @type {string} */
     message: ''
-  }
+  },
+  /** @return {{version: string}} */
+  getManifest: function() {}
 };
 
 /** @type {Object} */
 chrome.tabs;
 
 /** @param {function(chrome.Tab):void} callback */
 chrome.tabs.getCurrent = function(callback) {}
 
 /** @constructor */
 chrome.Tab = function() {
@@ skipping 11 matching lines @@
  *  @param {function(chrome.Window):void} callback */
 chrome.windows.get = function(id, getInfo, callback) {}
 
 /** @constructor */
 chrome.Window = function() {
   /** @type {string} */
   this.state = '';
   /** @type {string} */
   this.type = '';
 };