Scrim now scales with the album image

We accomplish this by baking it with the album art
with a LayerDrawable. This sizes the gradient based
on the album art instead of the ImageView, which
prevents it from changing as the view is squashed.

Test: Manual
Fixes: 231629489
Change-Id: I1e4fe6a19740c1f0244b74245150a2f18e9b513a