Fix underdraw during resizing

Since we hide the navigation bar background during resizing, we
need to fill it with the fallback background.

This was always an issue but somehow in OC we are displaying
garbage instead of black.

Test: Open Contacts/Dialer, resize, make sure no underdraw is
happening. Also test a couple of other apps.
Fixes: 36206155

Change-Id: I6b02060ef4acf36c2529d49063a61034f9261696