Don't show an error message if there isn't one.

remoting/webapp/crd/js/it2me_activity.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.
 
 /** @suppress {duplicate} */
 var remoting = remoting || {};
 
 (function() {
 
 'use strict';
@@ skipping 88 matching lines @@
 remoting.It2MeActivity.prototype.stop = function() {
   if (this.desktopActivity_) {
     this.desktopActivity_.stop();
   }
 };
 
 /**
  * @param {!remoting.Error} error
  */
 remoting.It2MeActivity.prototype.onConnectionFailed = function(error) {
-  this.showErrorMessage_(error);
+  // onConnectionFailed is also called if the connection is canceled, in which
+  // case no error message should be shown.
+  if (!error.isNone()) {
+    this.showErrorMessage_(error);
+  }
   base.dispose(this.desktopActivity_);
   this.desktopActivity_ = null;
 };
 
 /**
  * @param {!remoting.ConnectionInfo} connectionInfo
  */
 remoting.It2MeActivity.prototype.onConnected = function(connectionInfo) {
   this.accessCodeDialog_.inputField().value = '';
 };
@@ skipping 58 matching lines @@
 /**
  * @param {remoting.Host} host
  * @private
  */
 remoting.It2MeActivity.prototype.connect_ = function(host) {
   this.desktopActivity_.start(
       host, new remoting.CredentialsProvider({accessCode: this.passCode_}));
 };
 
 })();