Adjust OffscreenCanvas throttling to allow two frames of backlog

Adjust OffscreenCanvas throttling to allow two frames of backlog

The throttling fix landed in https://codereview.chromium.org/2817603004/
has severely impacted rendering throughput due to the delay in
compositor round trips.  To avoid blocking the renderer script's
animation loop, we need to allow the rendering proceed when there
is still a pending frame.

BUG=716138
Review-Url: https://codereview.chromium.org/2848553003
Cr-Commit-Position: refs/heads/master@{#468021}
Committed: https://chromium.googlesource.com/chromium/src/+/fa845ac545a12d519ab5cb7d7ba5d9fd57ae2a0c

[Justin Novosad, 2017-04-27 19:37:35]

junov@chromium.org changed reviewers:
+ eseckler@chromium.org

[Justin Novosad, 2017-04-27 19:37:36]

PTAL

[Justin Novosad, 2017-04-27 19:38:02]

The CQ bit was checked by junov@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2017-04-27 19:38:25]

Dry run: 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, 2017-04-27 20:03:42]

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

[commit-bot: I haz the power, 2017-04-27 20:03:43]

Dry run: Try jobs failed on following builders:
  cast_shell_linux on master.tryserver.chromium.linux (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.linux/builders/cast_shell_linu...)

[Eric Seckler, 2017-04-28 08:19:10]

lgtm!

https://codereview.chromium.org/2848553003/diff/1/third_party/WebKit/Source/p...
File
third_party/WebKit/Source/platform/graphics/OffscreenCanvasFrameDispatcherImpl.cpp
(right):

https://codereview.chromium.org/2848553003/diff/1/third_party/WebKit/Source/p...
third_party/WebKit/Source/platform/graphics/OffscreenCanvasFrameDispatcherImpl.cpp:31:
kMaxCompositorPendingFrames = 2,
same here?

https://codereview.chromium.org/2848553003/diff/1/third_party/WebKit/Source/p...
File
third_party/WebKit/Source/platform/graphics/OffscreenCanvasFrameDispatcherImpl.h
(right):

https://codereview.chromium.org/2848553003/diff/1/third_party/WebKit/Source/p...
third_party/WebKit/Source/platform/graphics/OffscreenCanvasFrameDispatcherImpl.h:67:
int compositor_pending_frames_ = 0;
nit: pending_compositor_frames_ ?

[Justin Novosad, 2017-04-28 14:20:17]

The CQ bit was checked by junov@chromium.org

[Justin Novosad, 2017-04-28 14:20:17]

The patchset sent to the CQ was uploaded after l-g-t-m from
eseckler@chromium.org
Link to the patchset: https://codereview.chromium.org/2848553003/#ps20001
(title: "better var names")

[commit-bot: I haz the power, 2017-04-28 14:20:37]

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, 2017-04-28 16:26:30]

CQ is committing da patch.

Bot data: {"patchset_id": 20001, "attempt_start_ts": 1493389217188890,
"parent_rev": "119717035c2dc30d8602465cbc1428eb72072c0d", "commit_rev":
"fa845ac545a12d519ab5cb7d7ba5d9fd57ae2a0c"}

[commit-bot: I haz the power, 2017-04-28 16:26:40]

Description was changed from

==========
Adjust OffscreenCanvas throttling to allow two frames of backlog

The throttling fix landed in https://codereview.chromium.org/2817603004/
has severely impacted rendering throughput due to the delay in
compositor round trips.  To avoid blocking the renderer script's
animation loop, we need to allow the rendering proceed when there
is still a pending frame.

BUG=716138
==========

to

==========
Adjust OffscreenCanvas throttling to allow two frames of backlog

The throttling fix landed in https://codereview.chromium.org/2817603004/
has severely impacted rendering throughput due to the delay in
compositor round trips.  To avoid blocking the renderer script's
animation loop, we need to allow the rendering proceed when there
is still a pending frame.

BUG=716138

Review-Url: https://codereview.chromium.org/2848553003
Cr-Commit-Position: refs/heads/master@{#468021}
Committed:
https://chromium.googlesource.com/chromium/src/+/fa845ac545a12d519ab5cb7d7ba5...
==========

[commit-bot: I haz the power, 2017-04-28 16:26:41]

Committed patchset #2 (id:20001) as
https://chromium.googlesource.com/chromium/src/+/fa845ac545a12d519ab5cb7d7ba5...