webrtc/examples/androidapp/res/layout/activity_call.xml

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

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

    <org.appspot.apprtc.PercentFrameLayout
        android:id="@+id/remote_video_layout"
        android:layout_width="match_parent"
        android:layout_height="match_parent">
        <org.webrtc.SurfaceViewRenderer
            android:id="@+id/remote_video_view"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content" />
    </org.appspot.apprtc.PercentFrameLayout>

    <org.appspot.apprtc.PercentFrameLayout
        android:id="@+id/local_video_layout"
        android:layout_width="match_parent"
        android:layout_height="match_parent">
        <org.webrtc.SurfaceViewRenderer
            android:id="@+id/local_video_view"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content" />
    </org.appspot.apprtc.PercentFrameLayout>

    <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" />

</RelativeLayout>