res/layout/dismiss_button.xml

<?xml version="1.0" encoding="utf-8"?>
<!--
  ~ Copyright (C) 2020 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">
    <FrameLayout
        style="@style/DismissButtonLayout"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content">
        <ImageButton
            android:id="@+id/dismiss_button"
            android:layout_width="@dimen/dismiss_button_diameter"
            android:layout_height="@dimen/dismiss_button_diameter"
            android:layout_marginLeft="@dimen/dismiss_button_horizontal_margin"
            android:layout_marginRight="@dimen/dismiss_button_horizontal_margin"
            android:layout_marginBottom="@dimen/card_min_bottom_padding"
            android:background="@drawable/dismiss_button_background"
            android:scaleType="center"
            android:src="@drawable/ic_clear"
            android:visibility="gone"/>
    </FrameLayout>
</merge>