Use event time instead of System.currentTimeMillis

As per the associated bugs, using system time is incorrect and can
result in flaky tests. This CL moves over to use event time.

Fix: 265023850
Test: manually verified that the shake animation still shows up if I tap
the quick affordance or slide my finger off of it
Test: manually verified that long-pressing the quick affordance still
works as expected

Change-Id: Ie4a45ade40690637e621b88f6a110fefa2af3216