examples/androidapp/res/layout/activity_call.xml

<?xml version="1.0" encoding="utf-8"?>

<!-- tools:ignore is needed because lint thinks this can be replaced with a merge. Replacing this
     with a merge causes the fullscreen SurfaceView not to be centered. -->
<FrameLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:ignore="MergeRootFrame">

    <org.webrtc.SurfaceViewRenderer
        android:id="@+id/fullscreen_video_view"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center" />

    <org.webrtc.SurfaceViewRenderer
        android:id="@+id/pip_video_view"
        android:layout_height="144dp"
        android:layout_width="wrap_content"
        android:layout_gravity="bottom|end"
        android:layout_margin="16dp"/>

    <FrameLayout
        android:id="@+id/call_fragment_container"
        android:layout_width="match_parent"
        android:layout_height="match_parent" />
    <FrameLayout
        android:id="@+id/hud_fragment_container"
        android:layout_width="match_parent"
        android:layout_height="match_parent" />

</FrameLayout>