Update some spinners on ChromeOS to Material.

chrome/browser/resources/extensions/chromeos/kiosk_apps.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. */
 
 #kiosk-apps-page .checkbox {
   display: block;
 }
 
 #kiosk-app-list {
   border: 1px solid lightgrey;
@@ skipping 100 matching lines @@
   vertical-align: middle;
 }
 
 .kiosk-app-icon {
   background-size: 100%;
   height: 16px;
   width: 16px;
 }
 
 .kiosk-app-icon.spinner {
-  background-image: url(chrome://resources/images/spinner.svg) !important;
+  background-image: url(chrome://resources/images/throbber.svg) !important;
 }
 
 .kiosk-app-name,
 .kiosk-app-status {
   overflow: hidden;
   text-overflow: ellipsis;
 }
 
 .kiosk-app-name {
   max-width: 250px;
@@ skipping 14 matching lines @@
   display: inline-block;
 }
 
 #kiosk-disable-bailout-confirm-overlay {
   width: 250px
 }
 
 #kiosk-disable-bailout-warning-bold {
   font-weight: bold;
 }