Using instrumented.identity.onSignInChanged to track signed-in state changes

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 375 matching lines @@
     instrumentChromeApiFunction: instrumentChromeApiFunction,
     registerWrapperPluginFactory: registerWrapperPluginFactory,
     checkInWrappedCallback: checkInWrappedCallback,
     debugGetStateString: debugGetStateString
   };
 })();
 
 wrapper.instrumentChromeApiFunction('alarms.get', 1);
 wrapper.instrumentChromeApiFunction('alarms.onAlarm.addListener', 0);
 wrapper.instrumentChromeApiFunction('identity.getAuthToken', 1);
+wrapper.instrumentChromeApiFunction('identity.onSignInChanged.addListener', 0);
 wrapper.instrumentChromeApiFunction('identity.removeCachedAuthToken', 1);
 
 /**
  * Builds the object to manage tasks (mutually exclusive chains of events).
  * @param {function(string, string): boolean} areConflicting Function that
  *     checks if a new task can't be added to a task queue that contains an
  *     existing task.
  * @return {Object} Task manager interface.
  */
 function buildTaskManager(areConflicting) {
@@ skipping 250 matching lines @@
   });
 
   return {
     start: start,
     planForNext: planForNext,
     stop: stop,
     isRunning: isRunning
   };
 }
 
-// TODO(robliao): Ideally, the authentication watcher infrastructure
-// below would be an API change to chrome.identity.
-// When this happens, remove the code below.
-
 /**
  * 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';
-
   /**
    * Determines if the user is signed in and provides a token if signed in.
    * @param {function(string=)} callback Called on completion.
    *     If the user is signed in, the string contains the token.
    */
   function isSignedIn(callback) {
     instrumented.identity.getAuthToken({interactive: false}, function(token) {
       token = chrome.runtime.lastError ? undefined : token;
       callback(token);
-      checkAndNotifyListeners(!!token);
     });
   }
 
   /**
    * Removes the specified cached token.
    * @param {string} token Authentication Token to remove from the cache.
    * @param {function} callback Called on completion.
    */
   function removeToken(token, callback) {
     instrumented.identity.removeCachedAuthToken({token: token}, function() {
-      // Removing the token from the cache will change the sign in state.
-      // Repoll now to check the state and notify listeners.
-      // This also lets Chrome now about a possible problem with the token.
+      // Attempting to get a fresh token will let Chrome know about a possible
+      // problem with the token.

[robliao, 2013/10/23 17:11:48]

Once Chrome gets a fresh token, will the onSignInChanged event fire?

       isSignedIn(function() {});
       callback();
     });
   }
 
-  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);
+    instrumented.identity.onSignInChanged.addListener(callback);
   }
 
-  /**
-   * Checks if the last signed in state matches the specified one.
-   * If it doesn't, it notifies the listeners of the change.
-   * @param {boolean} currentSignedInState The current signed in state.
-   */
-  function checkAndNotifyListeners(currentSignedInState) {
-    instrumented.storage.local.get('lastSignedInState', function(items) {
-      items = items || {};
-      if (items.lastSignedInState != currentSignedInState) {
-        chrome.storage.local.set(
-            {lastSignedInState: currentSignedInState});
-        if (items.lastSignedInState != undefined) {
-          listeners.forEach(function(callback) {
-            callback();
-          });
-        }
-      }
-    });
-  }
-
-  instrumented.alarms.onAlarm.addListener(function(alarm) {
-    if (alarm.name == alarmName)
-      isSignedIn(function() {});
-  });
-
-  // Poll for the sign in state every hour.
-  // One hour is just an arbitrary amount of time chosen.
-  chrome.alarms.create(alarmName, {periodInMinutes: 60});
-
   return {
     addListener: addListener,
     isSignedIn: isSignedIn,
     removeToken: removeToken
   };
 }