<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/messageHeaderView"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:layout_gravity="center_vertical|center_horizontal"
    android:gravity="center_vertical|center_horizontal"
    android:orientation="vertical" >

    <ProgressBar
        android:layout_width="wrap_content"
        android:layout_height="wrap_content" />

</LinearLayout>