packages/DocumentsUI/res/drawable/ic_breadcrumb_arrow_down.xml

<?xml version="1.0" encoding="utf-8"?>
<rotate xmlns:android="http://schemas.android.com/apk/res/android"
        android:fromDegrees="90"
        android:toDegrees="90"
        android:pivotX="50%"
        android:pivotY="50%"
        android:drawable="@drawable/ic_breadcrumb_arrow">
</rotate>