Fix index changed when no image in the directory in gallery

ui/file_manager/gallery/js/slide_mode.js

Index: ui/file_manager/gallery/js/slide_mode.js
diff --git a/ui/file_manager/gallery/js/slide_mode.js b/ui/file_manager/gallery/js/slide_mode.js
index 54ccfc190836c795c1f1bde488583cff4d7f9a5f..a74919151ae9d279722119a83c691609b3491ec7 100644
--- a/ui/file_manager/gallery/js/slide_mode.js
+++ b/ui/file_manager/gallery/js/slide_mode.js
@@ -927,6 +927,9 @@ SlideMode.prototype.getNextSelectedIndex_ = function(direction) {
  * @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');