support animated GIF

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 106 matching lines @@
   pointer-events: none;
   position: absolute;
   /* Duration and timing function are set in Javascript. */
   transition-property: transform, opacity;
 }
 
 .gallery .image-container > .image[fade] {
   opacity: 0;
 }
 
-/* Full resolution image is invisible unless printing. */
-.gallery .image-container > canvas.fullres {
-  opacity: 0;
-  position: absolute;
-}
-
 @media print {
   /* Do not print anything but the image content. */
   .gallery > :not(.content) {
     display: none !important;
   }
 
   /* Center the printed image. */
   .gallery .image-container {
     -webkit-box-align: center;
     -webkit-box-orient: horizontal;
     -webkit-box-pack: center;
     display: -webkit-box;
   }
 
-  /* Do not print the screen resolution image. */
-  .gallery .image-container > canvas.image {
-    display: none !important;
-  }
-
   /* Print the full resolution image instead. */
-  .gallery .image-container > canvas.fullres {
+  .gallery .image-container > .image {
     height: auto !important;
     max-height: 100%;
     max-width: 100%;
     opacity: 1 !important;
     position: static !important;
     transform: none !important;
     visibility: visible !important;
     width: auto !important;
   }
 }
@@ skipping 1168 matching lines @@
 .thumbnail-view .animation-thumbnail {
   background-repeat: no-repeat;
   background-size: cover;
   display: none;
   position: absolute;
 }
 
 .thumbnail-view .animation-thumbnail.animating {
   display: block;
 }