testapps/res/layout/self_managed_incoming_call.xml

<?xml version="1.0" encoding="utf-8"?>
<!--
  ~ Copyright (C) 2017 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
  -->

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical" android:layout_width="match_parent"
    android:layout_height="match_parent">

    <TextView
        android:text="Incoming Call!"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:id="@+id/incomingCallText" />

    <Button
        android:text="Answer Call"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:id="@+id/answerCallButton" />

    <Button
        android:text="Reject Call"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:id="@+id/rejectCallButton" />
</LinearLayout>