Signal-Android/app/src/main/res/layout/emoji_variation_selector.xml

<?xml version="1.0" encoding="utf-8"?>
<HorizontalScrollView
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content">

    <LinearLayout
        android:id="@+id/emoji_variation_container"
        android:orientation="horizontal"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content" />

</HorizontalScrollView>