Android: use grit target platform instead of define.

chrome/browser/resources/history/history.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[dir='rtl'] body.uber-frame > .page {
   -webkit-margin-end: 0;
 }
 
 #top-container {
   margin-top: 16px;
@@ skipping 241 matching lines @@
   min-width: 110px;
   width: 110px;
 }
 
 .entry input[type='checkbox'] {
   -webkit-margin-end: 6px;
   -webkit-margin-start: 4px;
   line-height: 1em;
 }
 
-<if expr="not pp_ifdef('android')">
+<if expr="not is_android">
 /* Checkboxes are shown when checked or focused, or when the entry is hovered.
  * Fade in on focus, but not on hover, because it makes the UI feel laggy. */
 .site-domain-wrapper input[type=checkbox]:not(:checked),
 .entry input[type='checkbox']:not(:checked) {
   opacity: 0;
 }
 
 .site-domain-wrapper:hover input[type='checkbox'],
 .site-domain-wrapper input[type='checkbox']:focus,
 .entry-box:hover input[type='checkbox'],
@@ skipping 261 matching lines @@
   background-image: url(../../../../ui/webui/resources/images/phone_small.png);
   background-position: 14px center;
   padding-left: 43px;
 }
 
 #action-menu[data-devicetype='tablet']::before {
   background-image: url(../../../../ui/webui/resources/images/tablet_small.png);
   background-position: 17px center;
   padding-left: 49px;
 }