WebVR: fix initial vsync

WebVR: fix initial vsync

Applications sometimes use window.rAF while not presenting, then switch to
vrDisplay.rAF after presentation starts. Depending on the animation loop's
timing, this can cause a race condition where presentation has been started
but there's no vrDisplay.rAF pending yet. Ensure there's at least vsync
being processed after presentation starts so that a queued window.rAF
can run and schedule a vrDisplay.rAF.

BUG=711789
NOTRY=true
NOPRESUBMIT=true

Review-Url: https://codereview.chromium.org/2848483003
Cr-Commit-Position: refs/heads/master@{#468167}
(cherry picked from commit 262e77a72493e36e8006aeeba1c7497a42ee5ad9)

Review-Url: https://codereview.chromium.org/2867813002
Cr-Commit-Position: refs/branch-heads/3071@{#454}
Cr-Branched-From: a106f0abbf69dad349d4aaf4bcc4f5d376dd2377-refs/heads/master@{#464641}
Committed: https://chromium.googlesource.com/chromium/src/+/83bc6712b5b740815f9b24dd10934656683cd5de

[klausw, 2017-05-08 17:51:14]

klausw@chromium.org changed reviewers:
+ bajones@chromium.org

[klausw, 2017-05-08 17:51:15]

(Requesting committer approval for merge)

[ddorwin, 2017-05-08 18:44:33]

ddorwin@chromium.org changed reviewers:
+ ddorwin@chromium.org

[ddorwin, 2017-05-08 18:44:34]

merge LGTM

[klausw, 2017-05-08 18:46:21]

The CQ bit was checked by klausw@chromium.org

[commit-bot: I haz the power, 2017-05-08 18:47:06]

CQ is trying da patch.

Follow status at:
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2017-05-08 18:47:07]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2017-05-08 18:47:07]

CLs for remote refs other than refs/heads/master must contain NOTRY=true and
NOPRESUBMIT=true in order for the CQ to process them

[klausw, 2017-05-08 18:48:00]

Description was changed from

==========
WebVR: fix initial vsync

Applications sometimes use window.rAF while not presenting, then switch to
vrDisplay.rAF after presentation starts. Depending on the animation loop's
timing, this can cause a race condition where presentation has been started
but there's no vrDisplay.rAF pending yet. Ensure there's at least vsync
being processed after presentation starts so that a queued window.rAF
can run and schedule a vrDisplay.rAF.

BUG=711789

Review-Url: https://codereview.chromium.org/2848483003
Cr-Commit-Position: refs/heads/master@{#468167}
(cherry picked from commit 262e77a72493e36e8006aeeba1c7497a42ee5ad9)
==========

to

==========
WebVR: fix initial vsync

Applications sometimes use window.rAF while not presenting, then switch to
vrDisplay.rAF after presentation starts. Depending on the animation loop's
timing, this can cause a race condition where presentation has been started
but there's no vrDisplay.rAF pending yet. Ensure there's at least vsync
being processed after presentation starts so that a queued window.rAF
can run and schedule a vrDisplay.rAF.

BUG=711789
NOTRY=true
NOPRESUBMIT=true

Review-Url: https://codereview.chromium.org/2848483003
Cr-Commit-Position: refs/heads/master@{#468167}
(cherry picked from commit 262e77a72493e36e8006aeeba1c7497a42ee5ad9)
==========

[klausw, 2017-05-08 18:48:06]

The CQ bit was checked by klausw@chromium.org

[commit-bot: I haz the power, 2017-05-08 18:48:42]

CQ is trying da patch.

Follow status at:
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2017-05-08 18:50:07]

CQ is committing da patch.

Bot data: {"patchset_id": 1, "attempt_start_ts": 1494269286425400, "parent_rev":
"1867c8fdf276d3045d79f720a3057350864b6dbe", "commit_rev":
"83bc6712b5b740815f9b24dd10934656683cd5de"}

[commit-bot: I haz the power, 2017-05-08 18:50:23]

Description was changed from

==========
WebVR: fix initial vsync

Applications sometimes use window.rAF while not presenting, then switch to
vrDisplay.rAF after presentation starts. Depending on the animation loop's
timing, this can cause a race condition where presentation has been started
but there's no vrDisplay.rAF pending yet. Ensure there's at least vsync
being processed after presentation starts so that a queued window.rAF
can run and schedule a vrDisplay.rAF.

BUG=711789
NOTRY=true
NOPRESUBMIT=true

Review-Url: https://codereview.chromium.org/2848483003
Cr-Commit-Position: refs/heads/master@{#468167}
(cherry picked from commit 262e77a72493e36e8006aeeba1c7497a42ee5ad9)
==========

to

==========
WebVR: fix initial vsync

Applications sometimes use window.rAF while not presenting, then switch to
vrDisplay.rAF after presentation starts. Depending on the animation loop's
timing, this can cause a race condition where presentation has been started
but there's no vrDisplay.rAF pending yet. Ensure there's at least vsync
being processed after presentation starts so that a queued window.rAF
can run and schedule a vrDisplay.rAF.

BUG=711789
NOTRY=true
NOPRESUBMIT=true

Review-Url: https://codereview.chromium.org/2848483003
Cr-Commit-Position: refs/heads/master@{#468167}
(cherry picked from commit 262e77a72493e36e8006aeeba1c7497a42ee5ad9)

Review-Url: https://codereview.chromium.org/2867813002
Cr-Commit-Position: refs/branch-heads/3071@{#454}
Cr-Branched-From:
a106f0abbf69dad349d4aaf4bcc4f5d376dd2377-refs/heads/master@{#464641}
Committed:
https://chromium.googlesource.com/chromium/src/+/83bc6712b5b740815f9b24dd1093...
==========

[commit-bot: I haz the power, 2017-05-08 18:50:24]

Committed patchset #1 (id:1) as
https://chromium.googlesource.com/chromium/src/+/83bc6712b5b740815f9b24dd1093...