res/layout/photo_set_item.xml

<?xml version="1.0" encoding="utf-8"?>
<FrameLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:background="?android:attr/activatedBackgroundIndicator"
    android:padding="2dip">

    <com.android.photos.views.SquareImageView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:id="@+id/thumbnail" />

</FrameLayout>