[Chromoting] Enable jscompile for webapp unittests.

remoting/webapp/unittests/chrome_mocks.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.
 
 // This file contains various mock objects for the chrome platform to make
 // unit testing easier.
 
 Entry = function() {};
 
 var chromeMocks = {};
 
+/** @constructor */
+chrome.Event = function() {};
+
+/** @param {Function} callback */
+chrome.Event.prototype.addListener = function(callback) {};
+
+/** @param {Function} callback */
+chrome.Event.prototype.removeListener = function(callback) {};
+
+
 (function(){
 
 /**
  * @constructor
  */
 chromeMocks.Event = function() {
   this.listeners_ = [];
 };
 
 /** @param {Function} callback */
@@ skipping 164 matching lines @@
   if (!originals_) {
     throw new Error('You must call activate() before restore().');
   }
   for (var components in originals_) {
     chrome[components] = originals_[components];
   }
   originals_ = null;
 };
 
 })();