Introduce a priority queue to the image loader.

chrome/browser/resources/image_loader/client.js

 // Copyright 2013 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.
 
 var ImageLoader = ImageLoader || {};
 
 /**
  * Image loader's extension id.
  * @const
  * @type {string}
@@ skipping 251 matching lines @@
 /**
  * Saves an image in the cache.
  *
  * @param {string} key Cache key.
  * @param {string} data Image data.
  * @param {number=} opt_timestamp Last modification timestamp. Used to detect
  *     if the cache entry becomes out of date.
  */
 ImageLoader.Client.Cache.prototype.saveImage = function(
     key, data, opt_timestamp) {
-
   // If the image is currently in cache, then remove it.
   if (this.images_[key])
     this.removeImage(key);
 
   if (ImageLoader.Client.Cache.MEMORY_LIMIT - this.size_ < data.length) {
     ImageLoader.Client.recordBinary('Evicted', 1);
     this.evictCache_(data.length);
   } else {
     ImageLoader.Client.recordBinary('Evicted', 0);
   }
@@ skipping 75 matching lines @@
       onError();
       return;
     }
     image.src = result.data;
     onSuccess();
   };
 
   return ImageLoader.Client.getInstance().load(
       url, callback, options, opt_isValid);
 };