In the future this can be implemented with a flush.

BUG=angleproject:2707

Change-Id: I1dd4eae9551f7797865e6e17e6caa77f6ec5a9b2
Reviewed-on: https://chromium-review.googlesource.com/1126457
Commit-Queue: Geoff Lang <geofflang@chromium.org>
Reviewed-by: Luc Ferron <lucferron@chromium.org>