Summary:
@public
EventBeat is an abstraction around proper event scheduling combining proper timing and proper threading. Event Queues use Event Beat to ensure that events are delivered on proper threads and in proper timing (probably batched). Consumers can `request` the next beat and `induce` immediatly beat.
MainRunLoopEventBeat implements particular Event Beat synchronized with the main event loop and calling a callback on the main thread.
Reviewed By: mdvacca
Differential Revision: D8886229
fbshipit-source-id: 1a42fcbf4cd61c6cb4c502890566c98b00226f31