White list of users is updated on show. Supervised users not present on the device are removed.

chrome/browser/resources/options/chromeos/accounts_options.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.
 
 cr.define('options', function() {
   var Page = cr.ui.pageManager.Page;
   var PageManager = cr.ui.pageManager.PageManager;
 
   /////////////////////////////////////////////////////////////////////////////
   // AccountsOptions class:
@@ skipping 63 matching lines @@
                                    !$('useWhitelistCheck').checked;
     },
 
     /**
      * Handler for Page's visible property change event.
      * @private
      * @param {Event} e Property change event.
      */
     handleVisibleChange_: function(e) {
       if (this.visible) {
+        chrome.send('updateWhitelist');
         this.updateControls_();
         if (this.showWhitelist_)
           $('userList').redraw();
       }
     },
 
     /**
      * Handler for allow guest check change.
      * @private
      */
     handleUseWhitelistCheckChange_: function(e) {
       // Whitelist existing users when guest login is being disabled.
       if ($('useWhitelistCheck').checked) {
-        chrome.send('whitelistExistingUsers');
+        chrome.send('updateWhitelist');
       }
 
       this.updateControls_();
     },
 
     /**
      * handler for allow guest pref change.
      * @private
      */
     handleUseWhitelistPrefChange_: function(e) {
@@ skipping 39 matching lines @@
     if (this.showWhitelist_)
       $('userList').updateAccountPicture(username);
   };
 
   // Export
   return {
     AccountsOptions: AccountsOptions
   };
 
 });