Introduce Image loader extension.

chrome/browser/resources/file_manager/js/image_editor/image_util.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.
 
 
 // Namespace object for the utilities.
 function ImageUtil() {}
 
 /**
  * Performance trace.
@@ skipping 469 matching lines @@
       this.image_.onload = null;
       if (ImageUtil.ImageLoader.isTooLarge(this.image_)) {
         errorCallback('IMAGE_TOO_BIG_ERROR');
         return;
       }
       transformFetcher(url, onTransform.bind(this, e.target));
     }.bind(this);
     // errorCallback has an optional error argument, which in case of general
     // error should not be specified
     this.image_.onerror = errorCallback.bind(this, 'IMAGE_ERROR');
-    this.remoteLoader_ = util.loadImage(this.image_, url);
+    this.taskId_ = util.loadImage(this.image_, url);
   }.bind(this);
   if (opt_delay) {
     this.timeout_ = setTimeout(startLoad, opt_delay);
   } else {
     startLoad();
   }
 };
 
 /**
  * @return {boolean} True if an image is loading.
@@ skipping 25 matching lines @@
   this.callback_ = null;
   if (this.timeout_) {
     clearTimeout(this.timeout_);
     this.timeout_ = null;
   }
   if (this.image_) {
     this.image_.onload = function() {};
     this.image_.onerror = function() {};
     this.image_.src = '';
   }
-  if (this.remoteLoader_) {
-    this.remoteLoader_.cancel();
-    this.remoteLoader_ = null;
-  }
+  if (this.taskId_)
+    util.cancelLoadImage(this.taskId_);
   this.generation_++;  // Silence the transform fetcher if it is in progress.
 };
 
 /**
  * @param {HTMLImageElement} image Image to be transformed.
  * @param {object} transform rransformation description to applay to the image.
  * @private
  */
 ImageUtil.ImageLoader.prototype.convertImage_ = function(image, transform) {
   var canvas = this.document_.createElement('canvas');
@@ skipping 131 matching lines @@
  * @return {string} Full name.
  */
 ImageUtil.getMetricName = function(name) {
   return 'PhotoEditor.' + name;
 };
 
 /**
  * Used for metrics reporting, keep in sync with the histogram description.
  */
 ImageUtil.FILE_TYPES = ['jpg', 'png', 'gif', 'bmp', 'webp'];