Signal-Android/res/layout/conversation_fragment.xml

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

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

    <android.support.v7.widget.RecyclerView
            android:id="@android:id/list"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:scrollbars="vertical"
            android:cacheColorHint="?conversation_background" />


    <!--suppress AndroidLintUnusedAttribute-->
    <View android:id="@+id/compose_divider"
          android:layout_width="match_parent"
          android:layout_height="2dp"
          android:layout_gravity="bottom"
          android:background="@drawable/compose_divider_background"
          android:alpha="0"
          android:visibility="invisible" />

    <android.support.design.widget.FloatingActionButton
        android:id="@+id/scroll_to_bottom_button"
        android:visibility="invisible"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginEnd="@dimen/scroll_to_bottom_button_margin_end"
        android:layout_marginRight="@dimen/scroll_to_bottom_button_margin_end"
        android:layout_marginBottom="@dimen/scroll_to_bottom_button_margin_bottom"
        android:layout_gravity="bottom|end"
        android:contentDescription="@string/conversation_fragment__scroll_to_the_bottom_content_description"
        android:src="@drawable/ic_keyboard_arrow_down_white_36dp" />

</FrameLayout>