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Rather than waiting for the page flip event to return the status, return
it right after it's determined, which is immediately after submitting the
page flip to the kernel. This requires splitting the page flip callback
into two callbacks, one that takes the status and one that takes the
presentation feedback. This should be familiar as the GLSurface API has
exactly the same separation.

This does not actually change when GbmSurfaceless passes the ACK along,
so there should be no visible change. Changing when the ACK is returned
from GbmSurfacless can be done but would also require changes to
viz::BufferQueue.

Bug: 851997
Test: unit tests, CrOS still renders

Change-Id: Ided422ca3065e431ca8c9a5909b3faae72d97cc5
Reviewed-on: https://chromium-review.googlesource.com/1104863Reviewed-by: Daniel Nicoara <dnicoara@chromium.org>
Commit-Queue: Michael Spang <spang@chromium.org>
Cr-Commit-Position: refs/heads/master@{#570067}