Made the animation logic more stable

We're now using the most recent state of the last attached location
for the animation start, since otherwise this could be flickering.
The animation could detoriate if the view wasn't attached
to the screen anymore as a result, which is fixed as well.

Bug: 154137987
Test: add media notification, observe
Change-Id: I1a6dfa651d676b3d620577fbd6c9e6a5d833dc0c