[Gallery] Add reload feature

ui/file_manager/gallery/js/gallery_scripts.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.
 
 // The include directives are put into Javascript-style comments to prevent
 // parsing errors in non-flattened mode. The flattener still sees them.
 // Note that this makes the flattener to comment out the first line of the
 // included file but that's all right since any javascript file should start
 // with a copyright comment anyway.
 
@@ skipping 59 matching lines @@
 //<include src="gallery_item.js">
 //<include src="gallery_util.js">
 //<include src="mosaic_mode.js">
 //<include src="ribbon.js">
 //<include src="slide_mode.js">
 
 // Exports
 window.ImageUtil = ImageUtil;
 window.ImageUtil.metrics = metrics;
 window.Gallery = Gallery;
-window.util = util;
+
+window.reload = reload;  // will be called by the background.
+window.gallery = gallery;  // for debug.
 
 })();