Enabled Mosaic view on each volume.

chrome/browser/resources/file_manager/css/gallery.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. */
 
 body {
   -webkit-user-select: none;
   font-family: Open Sans, Droid Sans Fallback, sans-serif;
   font-size: 84%;
   margin: 0;
 }
@@ skipping 1210 matching lines @@
 }
 
 .mosaic-tile .img-wrapper {
   bottom: 0;
   left: 0;
   position: absolute;
   right: 0;
   top: 0;
 }
 
-.mosaic-tile img {
-  -webkit-user-drag: none;
-  position: absolute;
+.mosaic-tile .img-wrapper[generic-thumbnail],
+.mosaic-tile .img-wrapper:not([generic-thumbnail]) canvas {
+  -webkit-animation: fadeIn ease-in 1;
+  -webkit-animation-duration: 500ms;
+  -webkit-animation-fill-mode: forwards;
+}
+
+@-webkit-keyframes fadeIn {
+  from {
+    opacity: 0;
+  }
+  to {
+    opacity: 1;
+  }
 }
 
 /* In order to do mode animated transitions smoothly we keep both mosaic and
   image-container but transparent. */
 .gallery:not([mode='mosaic']) .mosaic,
 .gallery:not([mode='slide']) .image-container {
   pointer-events: none;
 }
 
 .gallery:not([mode='slide']) .ribbon,
@@ skipping 52 matching lines @@
     url('../images/gallery/slideshow-pause.png') 1x,
     url('../images/gallery/2x/slideshow-pause.png') 2x);
 }
 
 .slideshow-toolbar > .slideshow-end {
   background-image: -webkit-image-set(
     url('../images/gallery/slideshow-end.png') 1x,
     url('../images/gallery/2x/slideshow-end.png') 2x);
   margin-left: -2px;
 }