Remove -webkit-*-before/after in:

chrome/browser/resources/chromeos/login/header_bar.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.
  */
 
 #login-header-bar {
-  -webkit-padding-after: 7px;
   border-bottom: 3px solid black;
   bottom: 0;
   left: 0;
+  padding-bottom: 7px;
   position: absolute;
   right: 0;
 }
 
 #login-header-bar {
-  -webkit-padding-before: 7px;
   /* Using copy of Ash launcher background with 0.8 opacity applied to it.
      Otherwise if opacity: 0.8 is set here it will affect button text as well.
      Have to position background differently so that opacity is not applied
      to child elements. */
   background-image: url('chrome://theme/IDR_LAUNCHER_BACKGROUND');
+  padding-top: 7px;
 }
 
 html[screen=lock] .login-header-bar-hidden,
 html[screen=oobe] .login-header-bar-hidden {
   opacity: 0;
 }
 
 html[screen=lock] .login-header-bar-animate-fast,
 html[screen=oobe] .login-header-bar-animate-fast {
   -webkit-transition: opacity 200ms ease-out;
@@ skipping 72 matching lines @@
 #login-header-bar #cancel-multiple-sign-in-button {
   /* TODO(dzhioev): replace with appropriate image when possible. */
   background-image: url('chrome://theme/IDR_PANEL_CLOSE');
 }
 
 .button-restricted {
   border: 1px solid transparent;
   color: white !important;
   opacity: 0.4 !important;
 }