Update some spinners on ChromeOS to Material.

ui/file_manager/gallery/css/gallery.css

 /* Copyright (c) 2014 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. */
 
 body {
   -webkit-user-select: none;
   font-size: 84%;
   margin: 0;
 }
 
@@ skipping 1093 matching lines @@
 
 .gallery .share-menu > div > img {
   display: block;
   margin-right: 5px;
 }
 
 /* Load spinner and error banner. */
 
 .gallery .spinner {
   background-image:
-      url(../../file_manager/foreground/images/common/spinner.svg);
+      url(chrome://resources/images/throbber.svg);
   background-size: 100%;
-  height: 16px;
+  height: 32px;

[Evan Stade, 2015/05/07 22:53:45]

This change is somewhat tangential to changing the asset, but I noticed the
gallery's spinner looked too small. The video player uses the spinner in a very
similar way and makes it 32x32, so I matched that here.

   left: 50%;
-  margin-left: -8px;
-  margin-top: -8px;
+  margin-left: -16px;
+  margin-top: -16px;
   position: absolute;
   top: 50%;
-  width: 16px;
+  width: 32px;
 }
 
 .gallery:not([spinner]) .spinner {
   display: none;
 }
 
 .gallery .error-banner {
   -webkit-box-align: center;
   -webkit-box-orient: horizontal;
   -webkit-box-pack: center;
@@ skipping 228 matching lines @@
   background-color: rgba(255, 0, 0, 0.3);
 }
 
 .debug-me .load-target-external-metadata::before {
   background-color: rgba(0, 255, 0, 0.3);
 }
 
 .debug-me .load-target-file-entry::before {
   background-color: rgba(0, 0, 255, 0.3);
 }