Convert Google Now's Authentication Manager to use Promises

chrome/browser/resources/google_now/utility.js

 // Copyright (c) 2013 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';
 
 /**
  * @fileoverview Utility objects and functions for Google Now extension.
  * Most important entities here:
  * (1) 'wrapper' is a module used to add error handling and other services to
@@ skipping 708 matching lines @@
 /**
  * Wraps chrome.identity to provide limited listening support for
  * the sign in state by polling periodically for the auth token.
  * @return {Object} The Authentication Manager interface.
  */
 function buildAuthenticationManager() {
   var alarmName = 'sign-in-alarm';
 
   /**
    * Gets an OAuth2 access token.
-   * @param {function(string=)} callback Called on completion.
-   *     The string contains the token. It's undefined if there was an error.
+   * @return {Promise} A promise to get the authentication token. If there is
+   *     no token, the request is rejected.
    */
-  function getAuthToken(callback) {
-    instrumented.identity.getAuthToken({interactive: false}, function(token) {
-      token = chrome.runtime.lastError ? undefined : token;
-      callback(token);
+  function getAuthToken() {
+    return new Promise(function(resolve, reject) {
+      instrumented.identity.getAuthToken({interactive: false}, function(token) {
+        if (chrome.runtime.lastError || !token) {
+          reject();
+        } else {
+          resolve(token);
+        }
+      });
     });
   }
 
   /**
    * Determines whether there is an account attached to the profile.
-   * @param {function(boolean)} callback Called on completion.
+   * @return {Promise} A promise to determine if there is an account attached
+   *     to the profile.
    */
-  function isSignedIn(callback) {
-    instrumented.webstorePrivate.getBrowserLogin(function(accountInfo) {
-      callback(!!accountInfo.login);
+  function isSignedIn() {
+    return new Promise(function(resolve) {
+      instrumented.webstorePrivate.getBrowserLogin(function(accountInfo) {
+        resolve(!!accountInfo.login);
+      });
     });
   }
 
   /**
    * Removes the specified cached token.
    * @param {string} token Authentication Token to remove from the cache.
-   * @param {function()} callback Called on completion.
+   * @return {Promise} A promise that resolves on completion.
    */
-  function removeToken(token, callback) {
-    instrumented.identity.removeCachedAuthToken({token: token}, function() {
-      // Let Chrome now about a possible problem with the token.

[rgustafson, 2014/02/13 21:31:40]

Keep the comment in, but now -> know. It's not immediately obvious why there's a
get call after removing it.

[robliao, 2014/02/13 21:41:33]

Done.

-      getAuthToken(function() {});
-      callback();
+  function removeToken(token) {
+    return new Promise(function(resolve) {
+      instrumented.identity.removeCachedAuthToken({token: token}, function() {
+        getAuthToken();
+        resolve();
+      });
     });
   }
 
   var listeners = [];
 
   /**
    * Registers a listener that gets called back when the signed in state
    * is found to be changed.
    * @param {function()} callback Called when the answer to isSignedIn changes.
    */
   function addListener(callback) {
     listeners.push(callback);
   }
 
   /**
    * Checks if the last signed in state matches the current one.
    * If it doesn't, it notifies the listeners of the change.
    */
   function checkAndNotifyListeners() {
     isSignedIn(function(signedIn) {

[rgustafson, 2014/02/13 21:31:40]

This doesn't have a parameter anymore. Needs more promise.

[robliao, 2014/02/13 21:41:33]

Indeed! Done.
On 2014/02/13 21:31:40, rgustafson wrote:

       instrumented.storage.local.get('lastSignedInState', function(items) {
         items = items || {};
         if (items.lastSignedInState != signedIn) {
           chrome.storage.local.set(
               {lastSignedInState: signedIn});
           listeners.forEach(function(callback) {
             callback();
           });
         }
       });
@@ skipping 13 matching lines @@
   // One hour is just an arbitrary amount of time chosen.
   chrome.alarms.create(alarmName, {periodInMinutes: 60});
 
   return {
     addListener: addListener,
     getAuthToken: getAuthToken,
     isSignedIn: isSignedIn,
     removeToken: removeToken
   };
 }