res/layout/fragment_picker_tab.xml

<?xml version="1.0" encoding="utf-8"?>
<!--
  ~ Copyright (C) 2021 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.
  -->
<FrameLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <androidx.recyclerview.widget.RecyclerView

        android:id="@+id/photo_list"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:clipToPadding="false"
        android:drawSelectorOnTop="true"
        android:overScrollMode="never"/>

    <FrameLayout
        android:id="@+id/picker_bottom_bar"
        android:layout_width="match_parent"
        android:layout_height="@dimen/picker_bottom_bar_size"
        android:layout_gravity="bottom"
        android:background="@color/picker_background_color"
        android:elevation="@dimen/picker_bottom_bar_elevation"
        android:visibility="gone">

        <Button
            android:id="@+id/button_view_selected"
            android:layout_width="wrap_content"
            android:layout_height="match_parent"
            android:layout_marginHorizontal="@dimen/picker_bottom_bar_horizontal_gap"
            android:layout_gravity="left"
            android:paddingVertical="@dimen/picker_bottom_bar_vertical_gap"
            android:drawableLeft="@drawable/ic_view_selected"
            android:text="@string/picker_view_selected"
            android:textAllCaps="false"
            app:iconPadding="@dimen/picker_bottom_bar_vertical_gap"
            style="?attr/borderlessButtonStyle"/>

        <Button
            android:id="@+id/button_add"
            android:layout_width="wrap_content"
            android:layout_height="match_parent"
            android:layout_marginHorizontal="@dimen/picker_bottom_bar_horizontal_gap"
            android:layout_gravity="right"
            android:paddingVertical="@dimen/picker_bottom_bar_vertical_gap"
            android:text="@string/add"
            android:textAllCaps="false"
            style="?attr/materialButtonStyle"/>

    </FrameLayout>
</FrameLayout>