SF: keep a reference vsync point before clearing timestamps

This will keep the vsync sequence numbering in case that the
the new vsync timeline matches the old one.

Bug: 329036771
Change-Id: Ib65ec3cd4230ffb7ab12cec1757c5d3e32f0b1f9
Test: com.android.uibench.microbenchmark.UiBenchInflatingHanListViewFlingMicrobenchmark
2 files changed