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.
-
+// TODO(robliao): Use signed-in state change watch API when it's available.
 /**
  * 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.
@@ skipping 47 matching lines @@
             {lastSignedInState: currentSignedInState});
         if (items.lastSignedInState != undefined) {
           listeners.forEach(function(callback) {
             callback();
           });
         }
       }
     });
   }
 
+  instrumented.identity.onSignInChanged.addListener(function() {
+    isSignedIn(function() {});
+  });
+
   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
   };
 }