Fix index changed when no image in the directory in gallery

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 909 matching lines @@
   } else {
     return advance(this.getSelectedIndex(), this.getItemCount_());
   }
 };
 
 /**
  * Advance the selection based on the pressed key ID.
  * @param {string} keyID Key of the KeyboardEvent.
  */
 SlideMode.prototype.advanceWithKeyboard = function(keyID) {
+  if (this.getItemCount_() === 0)
+    return;
+
   var prev = (keyID === 'ArrowUp' ||
               keyID === 'ArrowLeft' ||
               keyID === 'MediaTrackPrevious');
   this.advanceManually(prev ? -1 : 1);
 };
 
 /**
  * Advance the selection as a result of a user action (as opposed to an
  * automatic change in the slideshow mode).
  * @param {number} direction -1 for left, 1 for right.
@@ skipping 1193 matching lines @@
 /**
  * Handles mouse up events.
  * @param {!Event} event Wheel event.
  * @private
  */
 TouchHandler.prototype.onMouseUp_ = function(event) {
   if (event.button !== 0)
     return;
   this.clickStarted_ = false;
 };