ChromeOS: Implement EULA screen of material design OOBE.

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

 /* Copyright 2016 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. */
 
 :host {
+  background-color: white;
   display: flex;
   flex-direction: column;
   position: relative;
+  width: 582px;
 }
 
 .oobe-icon-div {
  --iron-icon-height: 20px;
  --iron-icon-width: 20px;
  color: var(--google-blue-500);
 }
 
 .oobe-header {
-  background-color: white;
   color: black;
   height: 150px;
 }
 
 .oobe-footer {
-  background-color: white;
   position: relative;
 }
 
 .header-container {
   padding: 50px 40px 18px;
 }
 
 .footer-container {
   overflow-y: auto;
   padding: 24px 40px 34px;
@@ skipping 24 matching lines @@
 }
 
 ::content h1.welcome-message-hint {
   color: rgba(0, 0, 0, 0.87);
   font-size: 12px;
   font-weight: normal;
   margin-bottom: 0;
 }