Update android:background color in SliceViewStle to make it have correct
color when Panel is in dark mode. Use the attr which will change
depends on theme, rather than contextual card background which is
defined by settings, to make it correct in more general case.
Fixes: 131927006
Test: Manual
Change-Id: I38733f5a53d38f70f925268efea7592bd0f48260
Contextual cards are not bound to homepage. Remove prefix homepage from
layout and theme names.
Next step: update names for some resource values (dimen/color etc)
Bug: 130250419
Test: rebuild
Change-Id: I5e901268462aaa37e00493080ae09af001784823