Centralize latency measurement of recents animation

So both legacy and shell transition use the same logic to log
the latency number.

Bug: 218847872
Test: Launch any app and swipe from bottom. The logcat should
      contain "LatencyTracker: ACTION_START_RECENTS_ANIMATION".
Change-Id: I5b28ca76f4a7b3d5a22ffc13f919c59003163e6b
2 files changed