Sync fling physics between Scroller/OverScroller

Bug 6793537

Have the default fling physics for Scroller follow the newer patterns
from OverScroller.

Make some constants determined by DisplayMetrics density in
OverScroller per-instance rather than static.

Change-Id: I5308e4bb8eca63e95cf3f1eee1ba4fa5391023b0
2 files changed