res/layout/notification_handle_bar.xml

<?xml version="1.0" encoding="utf-8"?>
<!--
**
** Copyright 2019, The Android Open Source Project
**
** Licensed under the Apache License, Version 2.0 (the "License");
** you may not use this file except in compliance with the License.
** You may obtain a copy of the License at
**
**     http://www.apache.org/licenses/LICENSE-2.0
**
** Unless required by applicable law or agreed to in writing, software
** distributed under the License is distributed on an "AS IS" BASIS,
** WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
** See the License for the specific language governing permissions and
** limitations under the License.
*/
-->

<merge xmlns:android="http://schemas.android.com/apk/res/android">
    <View
        android:id="@+id/handle_bar"
        android:layout_width="match_parent"
        android:layout_height="@dimen/notification_shade_handle_bar_height"
        android:layout_marginBottom="@dimen/notification_shade_handle_bar_margin_bottom"
        android:layout_marginEnd="@dimen/notification_shade_handle_bar_margin_start"
        android:layout_marginStart="@dimen/notification_shade_handle_bar_margin_end"
        android:layout_marginTop="@dimen/notification_shade_handle_bar_margin_top"
        android:background="@drawable/notification_handle_bar"/>
</merge>