Remove Gallery.Item when the corresponding entries are removed in file system.

ui/file_manager/gallery/js/gallery.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.
 
 /**
  * Overrided metadata worker's path.
  * @type {string}
  */
 ContentProvider.WORKER_SCRIPT = '/js/metadata_worker.js';
 
@@ skipping 13 matching lines @@
    * @private
    */
   this.metadataCache_ = metadataCache;
 
   /**
    * Directory where the image is saved if the image is located in a read-only
    * volume.
    * @type {DirectoryEntry}
    */
   this.fallbackSaveDirectory = null;
+
+  // Start to watch file system entries.
+  var watcher = new EntryListWatcher(this);
+  watcher.getEntry = function(item) { return item.getEntry(); };
 }
 
 /**
  * Maximum number of full size image cache.
  * @type {number}
  * @const
  * @private
  */
 GalleryDataModel.MAX_FULL_IMAGE_CACHE_ = 3;
 
@@ skipping 1010 matching lines @@
 };
 
 /**
  * Loads entries.
  * @param {!Array.<Entry>} entries Array of entries.
  * @param {!Array.<Entry>} selectedEntries Array of selected entries.
  */
 window.loadEntries = function(entries, selectedEntries) {
   gallery.load(entries, selectedEntries);
 };