shell/android/apk/res/values-v17/styles.xml

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

<!-- Copyright 2015 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.
 -->

<resources>
  <style name="Theme.Transparent" parent="android:Theme">
    <item name="android:windowIsTranslucent">true</item>
    <item name="android:windowBackground">@android:color/transparent</item>
    <item name="android:windowContentOverlay">@null</item>
    <item name="android:windowNoTitle">true</item>
    <item name="android:windowIsFloating">true</item>
    <item name="android:backgroundDimEnabled">false</item>
  </style>
</resources>