Add a flag to disable threaded scrolling

Add a flag to disable threaded scrolling

Now that most scroll paths are accelerated, we have minimal coverage of
main-thread scrolling performance. Add a flag that disables threaded
scrolling, allowing local testing of and (potentially) perf bot coverage
for main-thread scroll responsiveness.

This depends on the Blink change
https://codereview.chromium.org/564043003/.

BUG=414323
Committed: https://crrev.com/2eee6cb90276be4e16fe7f2cf898ec558863a2d1
Cr-Commit-Position: refs/heads/master@{#296725}

[jdduke (slow), 2014-09-22 20:56:10]

jdduke@chromium.org changed reviewers:
+ jam@chromium.org, rbyers@chromium.org

[jdduke (slow), 2014-09-22 20:56:10]

PTAL, thanks.

rbyers@: chrome/. I went ahead and added to about_flags as I imagine a few key
interested people may not have ready access to command line manipulation.
jam@: content/.

[Rick Byers, 2014-09-22 21:05:50]

lgtm with nit

https://codereview.chromium.org/571963003/diff/60001/chrome/app/generated_res...
File chrome/app/generated_resources.grd (right):

https://codereview.chromium.org/571963003/diff/60001/chrome/app/generated_res...
chrome/app/generated_resources.grd:6475: +        Disabled threaded handling of
scroll-related input events, forcing all such scroll events to be handled on the
main thread.
Random users read this and try to infer our product direction strategy from flag
descriptions (normally they represent unlaunched features).  I'd suggest adding
something like "This will dramatically hurt scrolling performance of most
websites and so is intended for testing purposes only".

[jdduke (slow), 2014-09-22 21:15:02]

https://codereview.chromium.org/571963003/diff/60001/chrome/app/generated_res...
File chrome/app/generated_resources.grd (right):

https://codereview.chromium.org/571963003/diff/60001/chrome/app/generated_res...
chrome/app/generated_resources.grd:6475: +        Disabled threaded handling of
scroll-related input events, forcing all such scroll events to be handled on the
main thread.
On 2014/09/22 21:05:50, Rick Byers wrote:
> Random users read this and try to infer our product direction strategy from
flag
> descriptions (normally they represent unlaunched features).  I'd suggest
adding
> something like "This will dramatically hurt scrolling performance of most
> websites and so is intended for testing purposes only".

Done.

[jdduke (slow), 2014-09-22 21:15:02]

https://codereview.chromium.org/571963003/diff/60001/chrome/app/generated_res...
File chrome/app/generated_resources.grd (right):

https://codereview.chromium.org/571963003/diff/60001/chrome/app/generated_res...
chrome/app/generated_resources.grd:6475: +        Disabled threaded handling of
scroll-related input events, forcing all such scroll events to be handled on the
main thread.
On 2014/09/22 21:05:50, Rick Byers wrote:
> Random users read this and try to infer our product direction strategy from
flag
> descriptions (normally they represent unlaunched features).  I'd suggest
adding
> something like "This will dramatically hurt scrolling performance of most
> websites and so is intended for testing purposes only".

Done.

[Rick Byers, 2014-09-22 21:24:18]

On 2014/09/22 21:15:02, jdduke wrote:
>
https://codereview.chromium.org/571963003/diff/60001/chrome/app/generated_res...
> File chrome/app/generated_resources.grd (right):
> 
>
https://codereview.chromium.org/571963003/diff/60001/chrome/app/generated_res...
> chrome/app/generated_resources.grd:6475: +        Disabled threaded handling
of
> scroll-related input events, forcing all such scroll events to be handled on
the
> main thread.
> On 2014/09/22 21:05:50, Rick Byers wrote:
> > Random users read this and try to infer our product direction strategy from
> flag
> > descriptions (normally they represent unlaunched features).  I'd suggest
> adding
> > something like "This will dramatically hurt scrolling performance of most
> > websites and so is intended for testing purposes only".
> 
> Done.

Thanks.  LGTM

[jam, 2014-09-23 05:12:59]

lgtm with inlining the method

https://codereview.chromium.org/571963003/diff/80001/content/renderer/render_...
File content/renderer/render_view_impl.cc (right):

https://codereview.chromium.org/571963003/diff/80001/content/renderer/render_...
content/renderer/render_view_impl.cc:425: static bool
ShouldUseThreadedScrolling() {
this should be inlined, we normally don't add methods to CommandLine::HasSwitch.
the caller also already has command_line

[jdduke (slow), 2014-09-23 19:17:37]

Patchset #6 (id:100001) has been deleted

[jdduke (slow), 2014-09-23 19:18:11]

https://codereview.chromium.org/571963003/diff/80001/content/renderer/render_...
File content/renderer/render_view_impl.cc (right):

https://codereview.chromium.org/571963003/diff/80001/content/renderer/render_...
content/renderer/render_view_impl.cc:425: static bool
ShouldUseThreadedScrolling() {
On 2014/09/23 05:12:59, jam wrote:
> this should be inlined, we normally don't add methods to
CommandLine::HasSwitch.
> the caller also already has command_line

Done.

[jdduke (slow), 2014-09-24 22:26:24]

The CQ bit was checked by jdduke@chromium.org

[commit-bot: I haz the power, 2014-09-24 22:27:19]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/571963003/140001

[commit-bot: I haz the power, 2014-09-24 23:48:51]

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

[commit-bot: I haz the power, 2014-09-24 23:48:52]

Try jobs failed on following builders:
  linux_chromium_rel_swarming on tryserver.chromium.linux
(http://build.chromium.org/p/tryserver.chromium.linux/builders/linux_chromium_...)

[jdduke (slow), 2014-09-25 00:10:18]

jdduke@chromium.org changed reviewers:
+ mpearson@chromium.org

[jdduke (slow), 2014-09-25 00:10:19]

mpearson@: Owner review for tools/metrics/histograms/histograms.xml? Thanks.

[Mark P, 2014-09-25 16:09:49]

rubber stamp lgtm

[jdduke (slow), 2014-09-25 16:32:12]

The CQ bit was checked by jdduke@chromium.org

[commit-bot: I haz the power, 2014-09-25 16:33:20]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/571963003/180001

[commit-bot: I haz the power, 2014-09-25 17:02:32]

Committed patchset #9 (id:180001) as 427b7c202ebbd013be5a261f09d2711bb7f8e6cd

[commit-bot: I haz the power, 2014-09-25 17:03:11]

Patchset 9 (id:??) landed as
https://crrev.com/2eee6cb90276be4e16fe7f2cf898ec558863a2d1
Cr-Commit-Position: refs/heads/master@{#296725}