[ChromeOS] Don't show empty account picker.

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

 /* Copyright (c) 2011 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 the Out of the box experience (OOBE) flow.
  */
 
 html,
 body {
   height: 100%;
@@ skipping 548 matching lines @@
   border: 0;
   color: #666;
   cursor: pointer;
   height: 24px;
   margin: 0;
   min-width: 0;
   padding: 0;
   vertical-align: middle;
 }
 
-.divider-vert {
-  background: url('chrome://theme/IDR_DIVIDER_VERT') center center no-repeat;
+.header-bar-item {
+  -webkit-padding-start: 15px;
+  background-image: url('chrome://theme/IDR_DIVIDER_VERT');
+  background-position: left center;
+  background-repeat: no-repeat;
   display: inline-block;
   height: 24px;
-  vertical-align: middle;
-  width: 15px;
 }
 
 #login-header-bar #shutdown-button {
   -webkit-padding-start: 24px;
   background-image: url('chrome://theme/IDR_ICON_POWER20');
   background-position: left center;
   background-repeat: no-repeat;
 }
 
 #login-header-bar #add-user-button {
   -webkit-padding-start: 24px;
   background-image: url('chrome://theme/IDR_ICON_ADD_USER20');
   background-position: left center;
   background-repeat: no-repeat;
 }
 
+html[dir=rtl] .header-bar-item,
 html[dir=rtl] #shutdown-button,
 html[dir=rtl] #add-user-button {
   background-position: right center;
 }
 
 body.login-display {
   margin: 0;
   padding: 0;
 }
 
@@ skipping 158 matching lines @@
 }
 
 .dropdown-overlay {
   bottom: 0;
   left: 0;
   position: fixed;
   right: 0;
   top: 0;
   z-index: 5;
 }