Fix recent panel defaulting to white on clean flash

Previously, recent panel would default to a solid
    white background on clean flash, until the user
    changed/reset the colors.  This fixes that issue,
    and the recent panel background now defaults to
    the proper semi-transparent white drawable (or
    semi-transparent black drawable if the TRDS
    state is switched).

Change-Id: Iea9d292596e8f4f51b55940e97e6597215ca58c2

Conflicts:
	packages/SystemUI/src/com/android/systemui/oserecent/RecentController.java