VelocityTracker Cleanups

This is a minor clean-up CL on changes made in recent CLs to make
VelocityTracker 1D (see ag/19911102 and ag/19921486).

Bug: 32830165
Test: build and tests unaffected
Change-Id: I36eead3e8191855a8c87fae5c1ef1fc9424ee6b9
2 files changed