fix how monkey adjust timestamps for motion events

Currently for motion events, monkey forces current system uptime
onto both down time and event time. This breaks ACTION_MOVE
events because the down time of it is supposed to be the time
when finger is down.

the new logic is:
* check down time, if it's invalid (<0), fill in uptime
* always update event time with a fresh uptime

Bug: 6424997

Change-Id: I0b445815a5015d48c08bebc921c572164874449d
1 file changed