Merge "Ensure that velocity tracker is never null." into rvc-dev am:...

Merge "Ensure that velocity tracker is never null." into rvc-dev am: 05df6a58 am: c53ba4e8 am: b453641e am: e5fea35c

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/11796856

Change-Id: I04865ec0b13ed83a0e3bd6bedbc7574ee0935f0a