support animated GIF

ui/file_manager/gallery/js/slide_mode.js

 // Copyright 2014 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.
 
 /**
  * Slide mode displays a single image and has a set of controls to navigate
  * between the images and to edit an image.
  *
  * @param {!HTMLElement} container Main container element.
  * @param {!HTMLElement} content Content container element.
@@ skipping 1023 matching lines @@
   var toMillions = function(number) {
     return Math.round(number / (1000 * 1000));
   };
 
   var metadata = item.getMetadataItem();
   if (metadata) {
     ImageUtil.metrics.recordSmallCount(ImageUtil.getMetricName('Size.MB'),
         toMillions(metadata.size));
   }
 
-  var canvas = this.imageView_.getCanvas();
+  var image = this.imageView_.getImage();
   ImageUtil.metrics.recordSmallCount(ImageUtil.getMetricName('Size.MPix'),
-      toMillions(canvas.width * canvas.height));
+      toMillions(image.width * image.height));
 
   var extIndex = entry.name.lastIndexOf('.');
   var ext = extIndex < 0 ? '' :
       entry.name.substr(extIndex + 1).toLowerCase();
   if (ext === 'jpeg') ext = 'jpg';
   ImageUtil.metrics.recordEnum(
       ImageUtil.getMetricName('FileType'), ext, ImageUtil.FILE_TYPES);
 
   // Enable or disable buttons for editing and printing.
   if (opt_error) {
@@ skipping 235 matching lines @@
  * @param {!GalleryItem} item Item to save the image.
  * @param {function()} callback Callback.
  * @private
  */
 SlideMode.prototype.saveCurrentImage_ = function(item, callback) {
   this.showSpinner_(true);
 
   var savedPromise = this.dataModel_.saveItem(
       this.volumeManager_,
       item,
-      this.imageView_.getCanvas(),
+      ImageUtil.ensureCanvas(this.imageView_.getImage()),
       this.overwriteOriginalCheckbox_.checked);
 
   savedPromise.then(function() {
     this.showSpinner_(false);
     this.flashSavedLabel_();
 
     // Record UMA for the first edit.
     if (this.imageView_.getContentRevision() === 1)
       ImageUtil.metrics.recordUserAction(ImageUtil.getMetricName('Edit'));
 
@@ skipping 737 matching lines @@
   var event = assertInstanceof(event, MouseEvent);
   var viewport = this.slideMode_.getViewport();
   if (!this.enabled_ || !viewport.isZoomed())
     return;
   this.stopOperation();
   viewport.setOffset(
       viewport.getOffsetX() + event.wheelDeltaX,
       viewport.getOffsetY() + event.wheelDeltaY);
   this.slideMode_.applyViewportChange();
 };