<?xml version="1.0" encoding="utf-8"?>
<layer-list xmlns:android="http://schemas.android.com/apk/res/android">

    <item android:id="@android:id/progress">
        <scale
            android:scaleWidth="100%"
            android:scaleGravity="center"
            android:drawable="@drawable/ptr_progress_primary_holo" />
    </item>

</layer-list>