tests/Assist/res/layout/keyguard_preview.xml

<?xml version="1.0" encoding="utf-8"?>
<!--
  ~ Copyright (C) 2015 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"
             android:layout_width="match_parent"
             android:layout_height="match_parent"
             android:orientation="vertical"
             android:background="#d3d3d3">

    <View
        android:id="@+id/background"
        android:layout_width="match_parent"
        android:layout_height="350dp"
        android:layout_gravity="bottom"
        android:elevation="30dp"
        android:background="#e0e0e0"/>

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="350dp"
        android:orientation="vertical"
        android:elevation="30dp"
        android:layout_gravity="bottom">

        <FrameLayout
            android:id="@+id/card1"
            android:layout_width="match_parent"
            android:layout_height="150dp"
            android:layout_marginStart="8dp"
            android:layout_marginEnd="8dp"
            android:layout_marginTop="16dp"
            android:elevation="3dp"
            android:background="@drawable/round_rect">
        </FrameLayout>

        <View
            android:id="@+id/card2"
            android:layout_width="match_parent"
            android:layout_height="200dp"
            android:layout_marginStart="8dp"
            android:layout_marginEnd="8dp"
            android:layout_marginTop="16dp"
            android:elevation="3dp"
            android:background="@drawable/round_rect"/>

    </LinearLayout>
</FrameLayout>