ChromeOS: Implement Update screen of material design OOBE.

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

 /* Copyright 2013 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. */
 
 #update {
   min-height: 423px;
   padding: 70px 17px 69px;    /* Screen has no controls. */
 }
 
+#oobe[md-mode] #update {
+  min-height: unset;
+  padding: unset;
+}
+
 #update #update-screen-curtain {
   -webkit-box-align: start;
   -webkit-box-pack: center;
 }
 
 #update #update-checking-progress {
   -webkit-box-align: start;
   -webkit-box-pack: center;
   color: #9c9c9c;
   display: -webkit-box;
@@ skipping 46 matching lines @@
 #update progress::-webkit-progress-value {
   background: #bbb;
 }
 
 #update .progress-message {
   color: #a3a3a3;
   font-size: 13px;
   margin-top: 4px;
   text-align: center;
 }