[cros] Login screen: remove user button visible when hovered.

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 178 matching lines @@
   min-width: 16px;
   opacity: 0;
   padding: 0;
   position: absolute;
   right: 14px;
   top: 14px;
   width: 16px;
 }
 
 .pod .remove-user-button:focus,
+.pod .remove-user-button:hover,
 .user-image:hover ~ .remove-user-button {
   opacity: 1;
 }
 
 .pod.focused .remove-user-button {
   /* Track shifting of .user-image on pod focus. */
   -webkit-transform: translateY(-1px);
   -webkit-transition: -webkit-transform 140ms ease;
   opacity: 1;
 }
@@ skipping 24 matching lines @@
   /* Width of .user-image. */
   width: 160px;
   z-index: 1;
 }
 
 .pod.focused .signed-in-indicator {
   /* Track shifting of .user-image on pod focus. */
   -webkit-transform: translateY(-1px);
   -webkit-transition: -webkit-transform 140ms ease;
 }