Summary:
Changelog: [internal]
EventPriority is backed by int, passing it by reference doesn't provide any performance benefits. Quite contrary, it can make it slower because of indirectness (in our case it is probably negligible).
Reviewed By: mdvacca
Differential Revision: D27938600
fbshipit-source-id: 37d1312627dd5a8f9012dfb35d21afe716a16ad7