Changed Notification shade's background alpha initial and final values
to be configurable.

Bug: 143372960
Test: manual - took before and after videos
Merged-In: Ia0b6a56859889d538e21f807a88bc5217d89e64a
Change-Id: Ia0b6a56859889d538e21f807a88bc5217d89e64a
2 files changed