Polish status bar launch animations.

This CL improves the ongoing call animation by:

1. Making sure that the status bar window matches its parent size during
   the animation, so that the expanding view is not clipped.
2. Expanding the view below the other status bar text.

See b/183229367#comment8 and #comment11 for before/after videos.

Bug: 183229367
Test: Create an ongoing call notification, tap it
Change-Id: Idfd8a43109584a4b21ad0a3e5f5e2028a87a9c60