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

<?xml version="1.0" encoding="utf-8"?>
<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="wrap_content"
    android:background="?selectableItemBackgroundBorderless"
    tools:layout_height="60dp">

    <androidx.appcompat.widget.AppCompatImageView
        android:id="@+id/emoji_image"
        android:layout_width="34dp"
        android:layout_height="34dp"
        android:layout_gravity="center"
        android:adjustViewBounds="true"
        android:scaleType="fitCenter"
        tools:src="@drawable/ic_emoji_smiley_24" />

</FrameLayout>