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

<?xml version="1.0" encoding="utf-8"?>
<!-- Copyright 2017 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">
    <item>
        <shape android:shape="rectangle">
            <solid android:color="@android:color/white" />
            <size android:height="4dp" android:width="4dp"/>
        </shape>
    </item>
    <item android:top="0dp" android:left="4dp">
        <shape android:shape="rectangle">
            <solid android:color="@color/modern_grey_200"/>
            <size android:height="4dp" android:width="4dp"/>
        </shape>
    </item>
    <item android:top="4dp" android:left="0dp">
        <shape android:shape="rectangle">
            <solid android:color="@color/modern_grey_200"/>
            <size android:height="4dp" android:width="4dp"/>
        </shape>
    </item>
    <item android:top="4dp" android:left="4dp">
        <shape android:shape="rectangle">
            <solid android:color="@android:color/white" />
            <size android:height="4dp" android:width="4dp"/>
        </shape>
    </item>
</layer-list>