Changes the keyboard background to a linear gradient.

ui/keyboard/resources/elements/kb-row.html

 <!--
   -- Copyright (c) 2013 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.
   -->
 
 <polymer-element name="kb-row" attributes="align">
   <template>
     <style>
     :host {
       text-align: center;
       margin-right: 0.25em;
       margin-top: 0.25em;
     }
     :host :last-of-type {
       margin-bottom: 0.25em;
     }
 
-    :host:nth-child(1)>:not(.dark) {
+    :host:nth-child(1)>:not(.dark):not(.active) {
       -webkit-box-shadow: inset 0px 1px #6f6f6f, inset 0px -1px #565656;
       background-image: -webkit-linear-gradient(#636363, #5b5b5b);
       background-size: cover;
       border-bottom-color: #4a4a4a;
       border-top-color: #878787;
     }
 
-    :host:nth-child(2)>:not(.dark) {
+    :host:nth-child(2)>:not(.dark):not(.active) {
       -webkit-box-shadow: inset 0px 1px #666666, inset 0px -1px #4c4c4c;
       background-image: -webkit-linear-gradient(#5a5a5a, #515151);
       background-size: cover;
       border-bottom-color: #414141;
       border-top-color: #7f7f7f;
     }
 
-    :host:nth-child(3)>:not(.dark) {
+    :host:nth-child(3)>:not(.dark):not(.active) {
       -webkit-box-shadow: inset 0px 1px #5d5d5d, inset 0px -1px #444444;
       background-image: -webkit-linear-gradient(#505050, #494949);
       background-size: cover;
       border-bottom-color: #3a3a3a;
       border-top-color: #787878;
     }
 
-    :host:nth-child(4)>:not(.dark) {
+    :host:nth-child(4)>:not(.dark):not(.active) {
       -webkit-box-shadow: inset 0px 1px #565656, inset 0px -1px #434343;
       background-image: -webkit-linear-gradient(#484848, #474747);
       background-size: cover;
       border-bottom-color: #393939;
       border-top-color: #717171;
     }
 
-    :host>:not(.dark) {
+    :host>:not(.dark):not(.active) {
       -webkit-box-shadow: inset 0px 1px #565656, inset 0px -1px #434343;
       background-image: -webkit-linear-gradient(#484848, #474747);
       background-size: cover;
       border-bottom-color: #393939;
       border-top-color: #717171;
     }
     </style>
     <content select="*"></content>
   </template>
   <script>
     Polymer('kb-row', {
       align: RowAlignment.STRETCH,
     });
   </script>
 </polymer-element>