[Webapp Refactor] Group authentications fields into remoting.CredentialsProvider.

remoting/webapp/crd/js/identity.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.
 
 /**
  * @fileoverview
  * Wrapper class for Chrome's identity API.
  */
 
 'use strict';
@@ skipping 139 matching lines @@
   });
 };
 
 /**
  * Gets the user's email address.
  *
  * @return {!Promise<string>} Promise resolved with the user's email
  *     address or rejected with a remoting.Error.
  */
 remoting.Identity.prototype.getEmail = function() {
-  this.getUserInfo().then(function(userInfo) {
+  return this.getUserInfo().then(function(userInfo) {
     return userInfo.email;
   });
 };
 
 /**
  * Gets the user's email address, or null if no successful call to
  * getUserInfo has been made.
  *
  * @return {?string} The cached email address, if available.
  */
@@ skipping 58 matching lines @@
 };
 
 /**
  * Returns whether the web app has authenticated with the Google services.
  *
  * @return {boolean}
  */
 remoting.Identity.prototype.isAuthenticated = function() {
   return remoting.identity.email_ !== '';
 };