Delay wallpaper load by 2 * average wallpaper load time.

chrome/browser/resources/chromeos/login/screen_account_picker.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 Account picker screen implementation.
  */
 
 login.createScreen('AccountPickerScreen', 'account-picker', function() {
   /**
    * Maximum number of offline login failures before online login.
    * @type {number}
    * @const
    */
   var MAX_LOGIN_ATTEMPTS_IN_POD = 3;
   /**
    * Whether to preselect the first pod automatically on login screen.
    * @type {boolean}
    * @const
    */
   var PRESELECT_FIRST_POD = true;
 
   return {
     EXTERNAL_API: [
       'loadUsers',
       'updateUserImage',
       'updateUserGaiaNeeded',
       'setCapsLockState',
-      'forceLockedUserPodFocus'
+      'forceLockedUserPodFocus',
+      'onWallpaperLoaded'
     ],
 
     /** @override */
     decorate: function() {
       login.PodRow.decorate($('pod-row'));
     },
 
     // Whether this screen is shown for the first time.
     firstShown_: true,
 
@@ skipping 132 matching lines @@
       $('pod-row').classList.toggle('capslock-on', enabled);
     },
 
     /**
      * Enforces focus on user pod of locked user.
      */
     forceLockedUserPodFocus: function() {
       var row = $('pod-row');
       if (row.lockedPod)
         row.focusPod(row.lockedPod, true);
+    },
+
+    /**
+     * Mark wallpaper loaded
+     */
+    onWallpaperLoaded: function(email) {
+      $('pod-row').onWallpaperLoaded(email);
     }
   };
 });