Delay wallpaper load by 2 * average wallpaper load time.

chrome/browser/resources/chromeos/login/screen_account_picker.js

Index: chrome/browser/resources/chromeos/login/screen_account_picker.js
diff --git a/chrome/browser/resources/chromeos/login/screen_account_picker.js b/chrome/browser/resources/chromeos/login/screen_account_picker.js
index 8405ee5ed3aeef298497dc50a94fb525eade407f..019e4dc843187c8d5909314a2003ce093eb18036 100644
--- a/chrome/browser/resources/chromeos/login/screen_account_picker.js
+++ b/chrome/browser/resources/chromeos/login/screen_account_picker.js
@@ -26,7 +26,8 @@ login.createScreen('AccountPickerScreen', 'account-picker', function() {
       'updateUserImage',
       'updateUserGaiaNeeded',
       'setCapsLockState',
-      'forceLockedUserPodFocus'
+      'forceLockedUserPodFocus',
+      'onWallpaperLoaded'
     ],
 
     /** @override */
@@ -188,6 +189,13 @@ login.createScreen('AccountPickerScreen', 'account-picker', function() {
       var row = $('pod-row');
       if (row.lockedPod)
         row.focusPod(row.lockedPod, true);
+    },
+
+    /**
+     * Mark wallpaper loaded
+     */
+    onWallpaperLoaded: function(username) {
+      $('pod-row').onWallpaperLoaded(username);
     }
   };
 });