am b5468f8e: More material updates to DocumentsUI.

<?xml version="1.0" encoding="utf-8"?>

<selector xmlns:android="http://schemas.android.com/apk/res/android">

    <item android:state_activated="true" android:color="?android:attr/colorAccent" />

    <item android:color="@*android:color/secondary_text_material_light" />

</selector>