Fix bug with login-prompt-visible not being sent in some rare cases.

chrome/browser/resources/chromeos/login/demo_user_login.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 Demo login UI.
  */
 
 /**
  * Handles a user clicking anywhere on the screen. This will log the demo user
  * in. Yes, this actually _is the intention.
  * @param {Event} e The click event that triggered this function.
  */
 onClick = function(e) {
   document.removeEventListener('click', onClick);
   e.stopPropagation();
   chrome.send('launchDemoUser');
 };
 
 /**
  * Initializes the click handler.
  */
 initialize = function() {
   $('page').style.opacity = 1;
   document.addEventListener('click', onClick);
   chrome.send('demoWebuiReady');
   // Report back sign in UI being painted.
   window.webkitRequestAnimationFrame(function() {
-    chrome.send('loginVisible');
+    chrome.send('loginVisible', ['demo']);
   });
 };
 
 disableTextSelectAndDrag();
 document.addEventListener('DOMContentLoaded', initialize);