Introduce a priority queue to the image loader.

chrome/browser/resources/file_manager/js/file_manager.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.
 
 'use strict';
 
 /**
  * This variable is checked in SelectFileDialogExtensionBrowserTest.
  * @type {number}
  */
@@ skipping 1288 matching lines @@
         // Preload a thumbnail if the new copied entry an image.
         var metadata = entry.getMetadata(function(metadata) {
           var url = entry.toURL();
           var thumbnailLoader_ = new ThumbnailLoader(
               url,
               ThumbnailLoader.LoaderType.CANVAS,
               metadata,
               undefined,  // Media type.
               FileType.isOnDrive(url) ?
                   ThumbnailLoader.UseEmbedded.USE_EMBEDDED :
-                  ThumbnailLoader.UseEmbedded.NO_EMBEDDED);
+                  ThumbnailLoader.UseEmbedded.NO_EMBEDDED,
+              10);  // Very low priority.
               thumbnailLoader_.loadDetachedImage(function(success) {});
         });
       }
     }
   };
 
   /**
    * Fills the file type list or hides it.
    * @private
    */
@@ skipping 2333 matching lines @@
    * Set the flag expressing whether the ctrl key is pressed or not.
    * @param {boolean} flag New value of the flag
    * @private
    */
   FileManager.prototype.setCtrlKeyPressed_ = function(flag) {
     this.ctrlKeyPressed_ = flag;
     this.document_.querySelector('#drive-clear-local-cache').canExecuteChange();
     this.document_.querySelector('#drive-reload').canExecuteChange();
   };
 })();