Gallery.app: Add buttons to the cropping mode to specifying the aspect ratio.

ui/file_manager/gallery/css/gallery.css

 /* Copyright (c) 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. */
 
 body {
   -webkit-user-select: none;
   font-family: Open Sans, Droid Sans Fallback, sans-serif;
   font-size: 84%;
   margin: 0;
 }
@@ skipping 820 matching lines @@
   display: none;
 }
 
 .gallery .edit-modal-wrapper {
   -webkit-box-align: center;
   -webkit-box-orient: horizontal;
   -webkit-box-pack: center;
   background-color: rgba(0, 0, 0, 0.75);
   color: white;
   display: -webkit-box;
-  padding-right: 5px;
   pointer-events: auto;
 }
 
 .gallery .edit-modal .label {
   -webkit-box-align: center;
   -webkit-box-orient: horizontal;
   background-position: 20px center;
   background-repeat: no-repeat;
   display: -webkit-box;
   height: 20px;
   padding-left: 50px;
   padding-right: 10px;
 }
 
 .gallery .edit-modal .label.brightness {
   background-image: -webkit-image-set(
       url(../images/100/icon_brightness.png) 1x,
       url(../images/200/icon_brightness.png) 2x);
 }
 
 .gallery .edit-modal .label.contrast {
   background-image: -webkit-image-set(
       url(../images/100/icon_contrast.png) 1x,
       url(../images/200/icon_contrast.png) 2x);
   height: 24px;
   margin-left: 15px;
 }
 
+.gallery .edit-modal button {
+  background: transparent;
+  border: 0 none;
+  border-image: none;
+  box-sizing: border-box;
+  color: #fff;
+  height: 100%;
+  min-width: 0;
+  padding: 8px 16px;
+}
+
+.gallery .edit-modal button * {
+  pointer-events: none;
+}
+
+.gallery .edit-modal button:hover {
+  background: #1f1f1f;
+  color: #fff;
+}
+
+.gallery .edit-modal button.selected,
+.gallery .edit-modal button:active {
+  background: #f0f0f0;
+  color: black;
+}
+
 .gallery .edit-modal .range {
   -webkit-appearance: none !important;
   height: 3px;
   margin-right: 10px;
   margin-top: 1px;
 }
 
 .gallery .edit-modal .range::-webkit-slider-thumb {
   -webkit-appearance: none;
   background-image: -webkit-image-set(
@@ skipping 447 matching lines @@
       url(chrome://resources/images/2x/apps/topbar_button_maximize.png) 2x)
       center;
 }
 
 .gallery > .header > .close-button {
   background: -webkit-image-set(
       url(chrome://resources/images/apps/topbar_button_close.png) 1x,
       url(chrome://resources/images/2x/apps/topbar_button_close.png) 2x)
       center;
 }