chrome/android/java/res/layout/preferences_action_bar_shadow.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. -->

<!-- The shadow found below the action bar in settings.-->
<merge
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools" >

    <ImageView
        android:id="@+id/shadow"
        android:layout_width="match_parent"
        android:layout_height="@dimen/action_bar_shadow_height"
        android:background="@drawable/modern_toolbar_shadow"
        android:visibility="gone"
        tools:ignore="ContentDescription" />

</merge>