Update the alignment of the chrome://apps theme attribution when theme is installed

chrome/browser/resources/ntp4/new_tab.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. */
 
 html {
   /* It's necessary to put this here instead of in body in order to get the
      background-size of 100% to work properly */
   height: 100%;
   overflow: hidden;
 }
@@ skipping 110 matching lines @@
 }
 
 #page-list {
   /* fill the apps-frame */
   display: -webkit-box;
   height: 100%;
 }
 
 #attribution {
   bottom: 0;
-  left: auto;
   margin-left: 8px;
   /* Leave room for the scrollbar. */
   margin-right: 13px;
   position: absolute;
-  right: 0;
-  text-align: left;
   z-index: -5;
 }
 
-/* For themes that right-align their images, we flip the attribution to the
- * left to avoid conflicts. */
-html[themegravity='right'] #attribution,
 html[dir='rtl'] #attribution {
   left: 0;
   right: auto;
   text-align: right;
 }
 
 #attribution > span {
   display: block;
 }
 
@@ skipping 265 matching lines @@
   padding: 0;
 }
 
 .other-sessions-promo-message:only-child {
   display: block;
 }
 
 .other-sessions-promo-message p {
   margin: 0;
 }