Introduce Image loader extension.

chrome/browser/resources/file_manager/js/photo/ribbon.js

 // 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.
 
 /**
  * Scrollable thumbnail ribbon at the bottom of the Gallery in the Slide mode.
  *
  * @param {Document} document Document.
  * @param {MetadataCache} metadataCache MetadataCache instance.
  * @param {cr.ui.ArrayDataModel} dataModel Data model.
@@ skipping 315 matching lines @@
  *
  * @param {Element} thumbnail Thumbnail element.
  * @param {string} url Image url.
  * @param {Object} metadata Metadata.
  * @private
  */
 Ribbon.prototype.setThumbnailImage_ = function(thumbnail, url, metadata) {
   new ThumbnailLoader(url, ThumbnailLoader.LoaderType.IMAGE, metadata).load(
       thumbnail.querySelector('.image-wrapper'),
       ThumbnailLoader.FillMode.FILL /* fill */,
+      ThumbnailLoader.OptimizationMode.NEVER_DISCARD,
       null /* success callback */,
       this.onThumbnailError_.bind(null, url));
 };
 
 /**
  * Content change handler.
  *
  * @param {Event} event Event.
  * @private
  */
@@ skipping 12 matching lines @@
  * @param {string} oldUrl Old url.
  * @param {string} newUrl New url.
  * @private
  */
 Ribbon.prototype.remapCache_ = function(oldUrl, newUrl) {
   if (oldUrl != newUrl && (oldUrl in this.renderCache_)) {
     this.renderCache_[newUrl] = this.renderCache_[oldUrl];
     delete this.renderCache_[oldUrl];
   }
 };