res/layout/live_wallpaper_preview.xml

<!--
  ~ Copyright (C) 2016 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">

    <FrameLayout
        android:id="@+id/loading"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:background="#ff000000"
        android:forceHasOverlappingRendering="false">

        <ProgressBar
            style="@android:style/Widget.Material.ProgressBar"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_gravity="center"
            android:indeterminate="true"/>

    </FrameLayout>

    <FrameLayout android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:fitsSystemWindows="true">

        <android.support.design.widget.CoordinatorLayout
            android:id="@+id/coordinator_layout"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_gravity="bottom">

            <RelativeLayout android:id="@+id/bottom_sheet"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:layout_gravity="bottom"
                android:minHeight="@dimen/preview_attribution_pane_expanded_height"
                android:orientation="vertical"
                android:background="@color/translucent_black"
                app:behavior_peekHeight="@dimen/preview_attribution_pane_collapsed_height"
                app:layout_behavior="android.support.design.widget.BottomSheetBehavior">

                <ImageButton android:id="@+id/preview_attribution_pane_arrow"
                    android:contentDescription="@string/expand_attribution_panel"
                    android:layout_width="48dp"
                    android:layout_height="48dp"
                    android:layout_alignParentEnd="true"
                    android:focusable="true"
                    android:clickable="true"
                    android:src="@drawable/ic_keyboard_arrow_up_white_24dp"
                    style="?android:attr/borderlessButtonStyle"/>

                <TextView
                    android:id="@+id/preview_attribution_pane_title"
                    android:layout_width="match_parent"
                    android:layout_height="wrap_content"
                    android:layout_gravity="start"
                    android:layout_marginStart="@dimen/preview_attribution_pane_content_side_margin"
                    android:layout_marginEnd="@dimen/preview_attribution_pane_content_side_margin"
                    android:layout_marginTop="@dimen/preview_attribution_pane_title_top_margin"
                    android:layout_toStartOf="@id/preview_attribution_pane_arrow"
                    android:ellipsize="end"
                    android:textAppearance="@style/AttributionPaneTitle"
                    android:forceHasOverlappingRendering="false"/>

                <TextView android:id="@+id/preview_attribution_pane_subtitle1"
                    android:layout_width="match_parent"
                    android:layout_height="wrap_content"
                    android:layout_marginStart="@dimen/preview_attribution_pane_content_side_margin"
                    android:layout_marginEnd="@dimen/preview_attribution_pane_content_side_margin"
                    android:layout_marginTop="@dimen/preview_attribution_pane_subtitle1_top_margin"
                    android:layout_below="@id/preview_attribution_pane_title"
                    android:layout_toStartOf="@id/preview_attribution_pane_arrow"
                    android:textAppearance="@android:style/TextAppearance.Material.Body1"
                    android:forceHasOverlappingRendering="false"/>

                <TextView android:id="@+id/preview_attribution_pane_subtitle2"
                    android:layout_width="match_parent"
                    android:layout_height="wrap_content"
                    android:textSize="@dimen/abc_text_size_caption_material"
                    android:layout_marginStart="@dimen/preview_attribution_pane_content_side_margin"
                    android:layout_marginEnd="@dimen/preview_attribution_pane_content_side_margin"
                    android:layout_marginTop="@dimen/preview_attribution_pane_subtitle2_top_margin"
                    android:layout_below="@id/preview_attribution_pane_subtitle1"
                    android:layout_toStartOf="@id/preview_attribution_pane_arrow"
                    android:textAppearance="@android:style/TextAppearance.Material.Caption"
                    android:forceHasOverlappingRendering="false"/>

                <Button android:id="@+id/preview_attribution_pane_explore_button"
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:textColor="?android:attr/colorAccent"
                    android:layout_marginLeft="@dimen/preview_attribution_pane_explore_left_margin"
                    android:layout_marginStart="@dimen/preview_attribution_pane_explore_left_margin"
                    android:layout_marginTop="@dimen/preview_attribution_pane_explore_top_margin"
                    android:layout_marginBottom="@dimen/preview_attribution_pane_explore_bottom_margin"
                    android:layout_below="@id/preview_attribution_pane_subtitle2"
                    android:layout_gravity="center_vertical"
                    style="?android:attr/borderlessButtonStyle"
                    android:forceHasOverlappingRendering="false"/>

                <View android:id="@id/spacer"
                    android:layout_width="match_parent"
                    android:layout_height="@dimen/preview_attribution_pane_spacer_height"
                    android:layout_below="@id/preview_attribution_pane_subtitle2"
                    android:visibility="gone"/>

            </RelativeLayout>

        </android.support.design.widget.CoordinatorLayout>

        <android.widget.Toolbar android:id="@+id/toolbar"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_gravity="top"
            android:paddingStart="@dimen/preview_toolbar_up_button_padding"
            android:paddingEnd="@dimen/preview_toolbar_set_wallpaper_button_end_padding"
            style="@style/TranslucentToolbarStyle"/>

    </FrameLayout>
</FrameLayout>