Converted remoting.Error from an enum to a class

remoting/webapp/unittests/mock_signal_strategy.js

 // Copyright 2015 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.
 
 'use strict';
 
 /** @suppress {duplicate} */
 var remoting = remoting || {};
 
 
@@ skipping 37 matching lines @@
   this.onIncomingStanzaCallback_ =
       onIncomingStanzaCallback ? onIncomingStanzaCallback
                                : function() {};
 };
 
 /** @return {remoting.SignalStrategy.State} */
 remoting.MockSignalStrategy.prototype.getState = function() {
   return this.state_;
 };
 
-/** @return {remoting.Error} */
+/** @return {!remoting.Error} */
 remoting.MockSignalStrategy.prototype.getError = function() {
   return remoting.Error.NONE;
 };
 
 /** @return {string} */
 remoting.MockSignalStrategy.prototype.getJid = function() {
   return this.jid_;
 };
 
 /** @return {remoting.SignalStrategy.Type} */
 remoting.MockSignalStrategy.prototype.getType = function() {
   return this.type_;
 };
 
 /**
  * @param {remoting.SignalStrategy.State} state
  */
 remoting.MockSignalStrategy.prototype.setStateForTesting = function(state) {
   this.state_ = state;
   this.onStateChangedCallback_(state);
 };