Add thumbnailMetadataItem to GalleryItem.

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 81 matching lines @@
   this.context_ = context;
 
   /**
    * @type {!VolumeManager}
    * @private
    * @const
    */
   this.volumeManager_ = volumeManager;
 
   /**
-   * @type {!MetadataCache}
-   * @private
-   * @const
-   */
-  this.metadataCache_ = context.metadataCache;
-
-  /**
    * @type {function(function())}
    * @private
    * @const
    */
   this.toggleMode_ = toggleMode;
 
   /**
    * @type {function(string):string}
    * @private
    * @const
@@ skipping 1750 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();
 };