chrome/android/java/res/drawable-v21/ntp_search_box.xml

<?xml version="1.0" encoding="utf-8"?>
<!--
     Copyright 2018 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.
-->
<ripple xmlns:android="http://schemas.android.com/apk/res/android"
    android:color="@color/modern_grey_400" >

    <item
        android:drawable="@drawable/modern_toolbar_text_box_background"/>

</ripple>