WebUI: Change checkbox vertical offset for Chromeos.

ui/webui/resources/css/widgets.css

 /* Copyright (c) 2012 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. */
 
 /* This file defines styles for form controls. The order of rule blocks is
  * important as there are some rules with equal specificity that rely on order
  * as a tiebreaker. These are marked with OVERRIDE. */
 
 /* Default state **************************************************************/
 
@@ skipping 47 matching lines @@
       -webkit-linear-gradient(#ededed, #ededed 38%, #dedede);
   background-position: right center;
   background-repeat: no-repeat;
 }
 
 html[dir='rtl'] select {
   background-position: center left;
 }
 
 input[type='checkbox'] {
+<if expr="chromeos">
+  bottom: 1px;
+</if>
+< expr="not chromeos">

[Dan Beam, 2014/09/05 17:42:33]

you're missing an if here... sorry, reviewer fail

   bottom: 2px;
+</if>
   height: 13px;
   position: relative;
   vertical-align: middle;
   width: 13px;
 }
 
 input[type='radio'] {
   /* OVERRIDE */
   border-radius: 100%;
   bottom: 3px;
@@ skipping 223 matching lines @@
   display: block;
 }
 
 :-webkit-any(.checkbox, .radio) label:hover {
   color: black;
 }
 
 label > input:disabled:-webkit-any([type='checkbox'], [type='radio']) ~ span {
   color: #999;
 }