chrome/android/java/res/drawable/website_settings_permission_spinner_item_background.xml

<?xml version="1.0" encoding="utf-8"?>

<!-- Copyright 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.
-->
<layer-list xmlns:android="http://schemas.android.com/apk/res/android">
  <!-- To achieve a single border along the bottom, draw a rectangle offset by
       1dp in all dimensions but the bottom. -->
  <item android:top="-1dp" android:right="-1dp" android:left="-1dp">
    <shape android:shape="rectangle" >
       <stroke android:width="1dip" android:color="#e5e5e5"/>
    </shape>
  </item>
  <item><bitmap android:gravity="right" android:src="@drawable/page_info_arrow_down" /></item>

</layer-list>