Introduce Image loader extension.

chrome/browser/resources/file_manager/js/photo/photo_import.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.
 
 document.addEventListener('DOMContentLoaded', function() {
   PhotoImport.load();
 });
 
 /**
  * The main Photo App object.
@@ skipping 321 matching lines @@
   frame.className = 'grid-frame';
   li.appendChild(frame);
 
   var box = this.document_.createElement('div');
   box.className = 'img-container';
   this.metadataCache_.get(entry, 'thumbnail|filesystem',
       function(metadata) {
         new ThumbnailLoader(entry.toURL(),
                             ThumbnailLoader.LoaderType.IMAGE,
                             metadata).
-            load(box, ThumbnailLoader.FillMode.FIT);
+            load(box, ThumbnailLoader.FillMode.FIT,
+            ThumbnailLoader.OptimizationMode.DISCARD_DETACHED);
       });
   frame.appendChild(box);
 
   var check = this.document_.createElement('div');
   check.className = 'check';
   li.appendChild(check);
 };
 
 /**
  * Handles the 'pick all/none' action.
@@ skipping 187 matching lines @@
 
 /** @override */
 GridSelectionController.prototype.getLastIndex = function() {
   var dm = this.grid_.dataModel;
   for (var index = dm.length - 1; index >= 0; index--) {
     if (dm.item(index).type == 'entry')
       return index;
   }
   return -1;
 };