Increase the opacity of arrows in the Photo Editor

chrome/browser/resources/file_manager/js/image_editor/gallery.css

 /*
  * Copyright (c) 2011 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.
  */
 
 body {
   margin: 0;
   -webkit-user-select: none;
   font-family: Open Sans,Droid Sans Fallback,sans-serif;
@@ skipping 170 matching lines @@
    overlaps it) */
 .gallery .arrow div{
   width: 105px;
   height: 193px;
   background-repeat: no-repeat;
   background-position: center center;
   opacity: 0;
 }
 
 .gallery[tools] .arrow[active] div{
-  opacity: 0.17;
+  opacity: 0.25;
 }
 
 .gallery[tools] .arrow[active] div:hover{
   opacity: 1;
 }
 
 .gallery .arrow.left div{
   background-image: url(../../images/gallery/arrow_left.png);
 }
 
@@ skipping 502 matching lines @@
 }
 
 .gallery .share-menu > div:hover {
   background-color: rgba(240,240,240,1);
 }
 
 .gallery .share-menu > div > img {
   margin-right: 5px;
   display: block;
 }