Change to idle-task implementations in toBlob

Change to idle-task implementations in toBlob

This is a combined revert of
https://codereview.chromium.org/1491653002
and https://codereview.chromium.org/1614173002. One more
additional edit is the addition of
"testRunner.dumpAsText();" in canvas-toBlob-defaultpng.html
and canvas-toBlob-toDataURL-race.js.

Reason for this revert is that we found out idle-task
performs much better (has less negative impacts on other
activities) than threaded implementation on majority of
machines.

BUG=581574
Committed: https://crrev.com/477b16c4b0051e183d22d3705faeebcb2cc0cc42
Cr-Commit-Position: refs/heads/master@{#371806}

[xlai (Olivia), 2016-01-26 23:07:31]

Created Revert of Removal all idle-task implementations in toBlob

[xlai (Olivia), 2016-01-27 01:28:26]

Description was changed from

==========
Revert of Removal all idle-task implementations in toBlob (patchset #2 id:20001
of https://codereview.chromium.org/1614173002/ )

Reason for revert:
I want to pull back the implementations for idle-tasks, because I find that it
is possible that this implementation is the one we should adopt in canvas.toBlob
instead of the other implementation.

Original issue's description:
> Removal all idle-task implementations in toBlob
> 
> BUG=564218
> 
> Committed: https://crrev.com/72fc4074be5f53812829e6272f5e246319f444bd
> Cr-Commit-Position: refs/heads/master@{#370908}

TBR=junov@chromium.org
# Not skipping CQ checks because original CL landed more than 1 days ago.
BUG=564218
==========

to

==========
Switch to idle-task implementations in toBlob

A recent regression alert in perf bot (http://crbug.com/581301) after
canvas.toBlob ships leads to a discovery that the
--enable-experimental-canvas-features flag was not enabled in
smoothness.tough_canvas_cases perf tests. This means that the previous
experimental data collected from the tough_canvas_cases/canvas_toBlob.html, as
well as the conclusion derived from the data (using threaded implementation
instead of idle-tasks implementation), are not valid. 

We run another round of experiments on perf trybots. Based time, based on the
valid data, we determine that idle-task implementation generally performs better
on smoothness than threaded implementation (even when Blink shared thread pool
is used). The difference can become 1~2ms on mean frame rate.


BUG=564218
==========

[xlai (Olivia), 2016-01-27 01:28:26]

xlai@chromium.org changed reviewers:
+ ajuma@chromium.org

[xlai (Olivia), 2016-01-27 01:37:29]

Description was changed from

==========
Switch to idle-task implementations in toBlob

A recent regression alert in perf bot (http://crbug.com/581301) after
canvas.toBlob ships leads to a discovery that the
--enable-experimental-canvas-features flag was not enabled in
smoothness.tough_canvas_cases perf tests. This means that the previous
experimental data collected from the tough_canvas_cases/canvas_toBlob.html, as
well as the conclusion derived from the data (using threaded implementation
instead of idle-tasks implementation), are not valid. 

We run another round of experiments on perf trybots. Based time, based on the
valid data, we determine that idle-task implementation generally performs better
on smoothness than threaded implementation (even when Blink shared thread pool
is used). The difference can become 1~2ms on mean frame rate.


BUG=564218
==========

to

==========
Switch to idle-task implementations in toBlob

A recent regression alert in perf bot (http://crbug.com/581301) after
canvas.toBlob ships leads to a discovery that the
--enable-experimental-canvas-features flag was not enabled in
smoothness.tough_canvas_cases perf tests. This means that the previous
experimental data collected from the tough_canvas_cases/canvas_toBlob.html, as
well as the conclusion derived from the data (using threaded implementation
instead of idle-tasks implementation), are not valid. 

We run another round of experiments on perf trybots. Based time, based on the
valid data, we determine that idle-task implementation generally performs better
on smoothness than threaded implementation (even when Blink shared thread pool
is used). The difference can become 1~2ms on mean frame rate.


BUG=581574
==========

[xlai (Olivia), 2016-01-27 01:38:01]

Description was changed from

==========
Switch to idle-task implementations in toBlob

A recent regression alert in perf bot (http://crbug.com/581301) after
canvas.toBlob ships leads to a discovery that the
--enable-experimental-canvas-features flag was not enabled in
smoothness.tough_canvas_cases perf tests. This means that the previous
experimental data collected from the tough_canvas_cases/canvas_toBlob.html, as
well as the conclusion derived from the data (using threaded implementation
instead of idle-tasks implementation), are not valid. 

We run another round of experiments on perf trybots. Based time, based on the
valid data, we determine that idle-task implementation generally performs better
on smoothness than threaded implementation (even when Blink shared thread pool
is used). The difference can become 1~2ms on mean frame rate.


BUG=581574
==========

to

==========
Change to idle-task implementations in toBlob

BUG=581574
==========

[xlai (Olivia), 2016-01-27 01:51:15]

Patchset #1 (id:1) has been deleted

[xlai (Olivia), 2016-01-27 01:54:31]

Patchset #1 (id:250001) has been deleted

[xlai (Olivia), 2016-01-27 02:41:26]

Hi Ali, as Justin is away for vacation, would you please help me review this CL?
Basically, it is a revert of a patch that removes all the idle-task
implementations. You could take a look at this letter
(https://groups.google.com/a/google.com/forum/#!topic/chrome-canvas/L9Ym2pjIplY)
where I explained the reason in an email sent to canvas team.

[ajuma, 2016-01-27 14:19:22]

ajuma@chromium.org changed reviewers:
+ jbroman@chromium.org

[ajuma, 2016-01-27 14:21:51]

This is roughly a combined revert of
https://crrev.com/72fc4074be5f53812829e6272f5e246319f444bd and
https://crrev.com/9cbf936a9bc9102b2c9f9a7f6311b53747c2bd52 right? Please mention
this in the description, but otherwise lgtm. 

+jbroman for core/ OWNERS.

[jbroman, 2016-01-27 15:05:26]

On 2016/01/27 at 14:21:51, ajuma wrote:
> This is roughly a combined revert of
https://crrev.com/72fc4074be5f53812829e6272f5e246319f444bd and
https://crrev.com/9cbf936a9bc9102b2c9f9a7f6311b53747c2bd52 right? Please mention
this in the description, but otherwise lgtm. 

And if it isn't just a revert, please point out what other changes you made.

[xlai (Olivia), 2016-01-27 15:59:15]

Description was changed from

==========
Change to idle-task implementations in toBlob

BUG=581574
==========

to

==========
Change to idle-task implementations in toBlob

This is a combined revert of https://codereview.chromium.org/1491653002 and
https://codereview.chromium.org/1614173002. One more additional edit is the
addition of "testRunner.dumpAsText();" in canvas-toBlob-defaultpng.html and
canvas-toBlob-toDataURL-race.js.

BUG=581574
==========

[xlai (Olivia), 2016-01-27 16:00:08]

Description was changed from

==========
Change to idle-task implementations in toBlob

This is a combined revert of https://codereview.chromium.org/1491653002 and
https://codereview.chromium.org/1614173002. One more additional edit is the
addition of "testRunner.dumpAsText();" in canvas-toBlob-defaultpng.html and
canvas-toBlob-toDataURL-race.js.

BUG=581574
==========

to

==========
Change to idle-task implementations in toBlob

This is a combined revert of https://codereview.chromium.org/1491653002
and https://codereview.chromium.org/1614173002. One more
additional edit is the addition of
"testRunner.dumpAsText();" in canvas-toBlob-defaultpng.html
and canvas-toBlob-toDataURL-race.js.

BUG=581574
==========

[xlai (Olivia), 2016-01-27 16:42:51]

Description was changed from

==========
Change to idle-task implementations in toBlob

This is a combined revert of https://codereview.chromium.org/1491653002
and https://codereview.chromium.org/1614173002. One more
additional edit is the addition of
"testRunner.dumpAsText();" in canvas-toBlob-defaultpng.html
and canvas-toBlob-toDataURL-race.js.

BUG=581574
==========

to

==========
Change to idle-task implementations in toBlob

This is a combined revert of https://codereview.chromium.org/1491653002
and https://codereview.chromium.org/1614173002. One more
additional edit is the addition of
"testRunner.dumpAsText();" in canvas-toBlob-defaultpng.html
and canvas-toBlob-toDataURL-race.js.

Reason for this revert is that we found out idle-task performs much better (has
less negative impacts on other activities) than threaded implementation on
majority of machines.

BUG=581574
==========

[xlai (Olivia), 2016-01-27 16:43:13]

Description was changed from

==========
Change to idle-task implementations in toBlob

This is a combined revert of https://codereview.chromium.org/1491653002
and https://codereview.chromium.org/1614173002. One more
additional edit is the addition of
"testRunner.dumpAsText();" in canvas-toBlob-defaultpng.html
and canvas-toBlob-toDataURL-race.js.

Reason for this revert is that we found out idle-task performs much better (has
less negative impacts on other activities) than threaded implementation on
majority of machines.

BUG=581574
==========

to

==========
Change to idle-task implementations in toBlob

This is a combined revert of https://codereview.chromium.org/1491653002
and https://codereview.chromium.org/1614173002. One more
additional edit is the addition of
"testRunner.dumpAsText();" in canvas-toBlob-defaultpng.html
and canvas-toBlob-toDataURL-race.js.

Reason for this revert is that we found out idle-task
performs much better (has less negative impacts on other
activities) than threaded implementation on majority of
machines.

BUG=581574
==========

[xlai (Olivia), 2016-01-27 16:43:38]

Description was changed from

==========
Change to idle-task implementations in toBlob

This is a combined revert of https://codereview.chromium.org/1491653002
and https://codereview.chromium.org/1614173002. One more
additional edit is the addition of
"testRunner.dumpAsText();" in canvas-toBlob-defaultpng.html
and canvas-toBlob-toDataURL-race.js.

Reason for this revert is that we found out idle-task
performs much better (has less negative impacts on other
activities) than threaded implementation on majority of
machines.

BUG=581574
==========

to

==========
Change to idle-task implementations in toBlob

This is a combined revert of
https://codereview.chromium.org/1491653002
and https://codereview.chromium.org/1614173002. One more
additional edit is the addition of
"testRunner.dumpAsText();" in canvas-toBlob-defaultpng.html
and canvas-toBlob-toDataURL-race.js.

Reason for this revert is that we found out idle-task
performs much better (has less negative impacts on other
activities) than threaded implementation on majority of
machines.

BUG=581574
==========

[xlai (Olivia), 2016-01-27 16:46:14]

@ajuma, @jbroman: Yes, this is a combined revert with a few more trivial edits.
I included it in the description.

[jbroman, 2016-01-27 16:49:17]

lgtm

[xlai (Olivia), 2016-01-27 16:51:34]

The CQ bit was checked by xlai@chromium.org

[commit-bot: I haz the power, 2016-01-27 16:52:46]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1637163002/270001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1637163002/270001

[commit-bot: I haz the power, 2016-01-27 16:59:21]

Description was changed from

==========
Change to idle-task implementations in toBlob

This is a combined revert of
https://codereview.chromium.org/1491653002
and https://codereview.chromium.org/1614173002. One more
additional edit is the addition of
"testRunner.dumpAsText();" in canvas-toBlob-defaultpng.html
and canvas-toBlob-toDataURL-race.js.

Reason for this revert is that we found out idle-task
performs much better (has less negative impacts on other
activities) than threaded implementation on majority of
machines.

BUG=581574
==========

to

==========
Change to idle-task implementations in toBlob

This is a combined revert of
https://codereview.chromium.org/1491653002
and https://codereview.chromium.org/1614173002. One more
additional edit is the addition of
"testRunner.dumpAsText();" in canvas-toBlob-defaultpng.html
and canvas-toBlob-toDataURL-race.js.

Reason for this revert is that we found out idle-task
performs much better (has less negative impacts on other
activities) than threaded implementation on majority of
machines.

BUG=581574
==========

[commit-bot: I haz the power, 2016-01-27 16:59:22]

Committed patchset #1 (id:270001)

[commit-bot: I haz the power, 2016-01-27 17:00:28]

Description was changed from

==========
Change to idle-task implementations in toBlob

This is a combined revert of
https://codereview.chromium.org/1491653002
and https://codereview.chromium.org/1614173002. One more
additional edit is the addition of
"testRunner.dumpAsText();" in canvas-toBlob-defaultpng.html
and canvas-toBlob-toDataURL-race.js.

Reason for this revert is that we found out idle-task
performs much better (has less negative impacts on other
activities) than threaded implementation on majority of
machines.

BUG=581574
==========

to

==========
Change to idle-task implementations in toBlob

This is a combined revert of
https://codereview.chromium.org/1491653002
and https://codereview.chromium.org/1614173002. One more
additional edit is the addition of
"testRunner.dumpAsText();" in canvas-toBlob-defaultpng.html
and canvas-toBlob-toDataURL-race.js.

Reason for this revert is that we found out idle-task
performs much better (has less negative impacts on other
activities) than threaded implementation on majority of
machines.

BUG=581574

Committed: https://crrev.com/477b16c4b0051e183d22d3705faeebcb2cc0cc42
Cr-Commit-Position: refs/heads/master@{#371806}
==========

[commit-bot: I haz the power, 2016-01-27 17:00:28]

Patchset 1 (id:??) landed as
https://crrev.com/477b16c4b0051e183d22d3705faeebcb2cc0cc42
Cr-Commit-Position: refs/heads/master@{#371806}