Support latency metrics for recents gesture

Accpet the event time from RecentsAnimation#startRecentsActivity.
Also remove unused method of recents animation in activity manager.

Bug: 169221287
Test: Enable statsd log: "adb shell cmd stats print-logs"
      Touch gesture navigation bar.
      adb logcat | grep statsd | grep "(48)"
      The line may contain 0x100000->4[I] 0x110000->20[I]
      that means 4=by recents and 20=latency 20ms.

Change-Id: Ia188a6a3b0dab9edaa0052df3b18508f8cc895d3