Summary:
We want to be able to instrument touch processing delays in JS, which does not have access to systemUptime; therefore we want a UNIX timestamp, which JS has access to and can compare to the touch time.
It only matters that there is relative consistency between multiple touch events in JS, which is still the case; so this should have no impact on product code.
Changelog: [Internal]
Reviewed By: sammy-SC
Differential Revision: D26705430
fbshipit-source-id: 2acd52ae5873a44edf1e0cb126a9a6c87203d8fa
b08362ade5