Add stub icons for playpen.

chrome/browser/resources/chromeos/login/user_pod_row.css

 /* 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.
  *
  * This is the stylesheet used by user pods row of account picker UI.
  */
 
 podrow {
   -webkit-box-align: center;
   -webkit-box-pack: center;
@@ skipping 204 matching lines @@
   outline: none;
   padding: 0;
   position: absolute;
   top: 0;
   width: 26px;
   z-index: 1;
 }
 
 .user-type-icon-image {
   background-color: transparent;
-  background-image: url('chrome://theme/IDR_OOBE_ACTION_BOX_BUTTON_NORMAL');
+  background-image: url('chrome://theme/IDR_MANAGED_MODE_ICON');
   border: 0 !important;
   height: 16px;

[Nikita (slow), 2013/05/27 15:46:46]

It is the same 16x16 icon, right?

[Denis Kuznetsov (DE-MUC), 2013/05/27 15:49:19]

Yes.

   margin: 5px;
   padding: 0;
   width: 16px;
 }
 
-
 html[dir=rtl] .action-box-area {
   left: 0;
   right: auto;
 }
 
 .action-box-button:hover {
   background-image: url('chrome://theme/IDR_OOBE_ACTION_BOX_BUTTON_HOVER');
 }
 
 .action-box-area.active .action-box-button {
@@ skipping 201 matching lines @@
 .pod.public-account.expanded .name,
 .pod.public-account.expanded .learn-more {
   display: none;
 }
 
 .pod.public-account.expanded .side-pane-divider,
 .pod.public-account.expanded .side-pane-container,
 .pod.public-account.animating .side-pane-container {
   visibility: inherit;
 }