packages/SystemUI/res/layout/status_bar_notification_row.xml

<com.android.systemui.statusbar.ExpandableNotificationRow
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:focusable="true"
    android:clickable="true"
    >

    <com.android.systemui.statusbar.NotificationContentView android:id="@+id/expanded"
       android:layout_width="match_parent"
       android:layout_height="wrap_content" />

    <com.android.systemui.statusbar.NotificationContentView android:id="@+id/expandedPublic"
        android:layout_width="match_parent"
        android:layout_height="wrap_content" />

    <Button
        android:id="@+id/veto"
        android:layout_width="48dp"
        android:layout_height="match_parent"
        android:gravity="end"
        android:layout_marginEnd="-80dp"
        android:background="@null"
        android:paddingEnd="8dp"
        android:paddingStart="8dp"
        />

    <TextView
        android:id="@+id/debug_info"
        android:visibility="invisible"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="bottom|end"
        android:fontFamily="sans-serif-condensed"
        android:textSize="9dp"
        android:textStyle="bold"
        android:textColor="#00A040"
        android:padding="2dp"
        />

</com.android.systemui.statusbar.ExpandableNotificationRow>