Introduce Image loader extension.

chrome/browser/resources/file_manager/css/photo_import.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. */
 
 .photo-import {
   -webkit-user-select: none;
   bottom: 0;
   font-family: Noto Sans UI, Droid Sans Fallback, sans-serif;
   font-size: 84%;
   left: 0;
@@ skipping 133 matching lines @@
   position: relative;
   width: 100%;
 }
 
 .img-container > img {
   -webkit-user-drag: none;
   box-sizing: border-box;
   position: absolute;
 }
 
+.img-container > img:not(.cached) {
+  -webkit-animation: fadeIn ease-in 1;
+  -webkit-animation-duration: 100ms;
+  -webkit-animation-fill-mode: forwards;
+}
+
+@-webkit-keyframes fadeIn {
+  from {
+    opacity: 0;
+  }
+  to {
+    opacity :1;
+  }
+}
+
 .grid-item[lead] {
   border: 2px solid transparent !important;
 }
 
 .grid-item[selected],
 .grid-item[lead][selected],
 .grid-item:hover {
   border: 2px solid rgb(51, 153, 255) !important;
 }
 
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   font-size: 90%;
   min-height: 26px;
   min-width: 87px;
   position: absolute;
   right: 10px;
 }
 
 .importing-dialog .progress-bar {
   -webkit-box-flex: 1;
 }