Added experiment for changing viewport scroll ordering.

Added experiment for changing viewport scroll ordering.

This is the first in a series of patches to experiment with modifying how the
Blink viewport scrolls. This patch adds a command-line flag, about:flags
experiment and Chromium-side setting for the experiment and implements the
first change related to the experiment: limiting scrolling on a pinch-zoom
gesture to the visual (inner) viewport only.

BUG=443724
CQ_INCLUDE_TRYBOTS=tryserver.blink:linux_blink_rel

Committed: https://crrev.com/9e55696155786e6e64045d594c5fc3720e979fd5
Cr-Commit-Position: refs/heads/master@{#333540}

[bokan, 2015-06-05 18:30:03]

Hi Alexandre, ptal.

[bokan, 2015-06-08 15:47:20]

bokan@chromium.org changed reviewers:
+ aelias@chromium.org

[bokan, 2015-06-08 15:47:21]

+aelias@

[aelias_OOO_until_Jul13, 2015-06-09 04:02:44]

lgtm modulo nits

https://codereview.chromium.org/1146053009/diff/40001/chrome/app/generated_re...
File chrome/app/generated_resources.grd (right):

https://codereview.chromium.org/1146053009/diff/40001/chrome/app/generated_re...
chrome/app/generated_resources.grd:6769: +        Enables fliped viewport scroll
order in some situations. Namely, during a pinch-zoom, the visual viewport
should be scrolled first, then the layout viewport.
spelling: "flipped"

https://codereview.chromium.org/1146053009/diff/40001/content/public/common/c...
File content/public/common/content_switches.cc (right):

https://codereview.chromium.org/1146053009/diff/40001/content/public/common/c...
content/public/common/content_switches.cc:493:
"enable-viewport-scroll-order-experiment";
I think "invert-viewport-scroll-order" would be clearer and more concise?

[bokan, 2015-06-09 11:49:04]

https://codereview.chromium.org/1146053009/diff/40001/chrome/app/generated_re...
File chrome/app/generated_resources.grd (right):

https://codereview.chromium.org/1146053009/diff/40001/chrome/app/generated_re...
chrome/app/generated_resources.grd:6769: +        Enables fliped viewport scroll
order in some situations. Namely, during a pinch-zoom, the visual viewport
should be scrolled first, then the layout viewport.
On 2015/06/09 04:02:44, aelias wrote:
> spelling: "flipped"

Done.

https://codereview.chromium.org/1146053009/diff/40001/content/public/common/c...
File content/public/common/content_switches.cc (right):

https://codereview.chromium.org/1146053009/diff/40001/content/public/common/c...
content/public/common/content_switches.cc:493:
"enable-viewport-scroll-order-experiment";
On 2015/06/09 04:02:44, aelias wrote:
> I think "invert-viewport-scroll-order" would be clearer and more concise?

sgtm, done.

[bokan, 2015-06-09 11:51:56]

bokan@chromium.org changed reviewers:
+ avi@chromium.org, kenrb@chromium.org

[bokan, 2015-06-09 11:51:57]

+kenrb@ for common_param_traits_macros
+avi@ for content/public and content/renderer

[kenrb, 2015-06-09 13:55:55]

ipc lgtm

[Avi (use Gerrit), 2015-06-09 14:40:26]

LGTM with comment fix.

https://codereview.chromium.org/1146053009/diff/60001/content/public/common/c...
File content/public/common/content_switches.cc (right):

https://codereview.chromium.org/1146053009/diff/60001/content/public/common/c...
content/public/common/content_switches.cc:610: // and portrait mode (i.e.
Android) so the page should be rescaled to fit
s/are the caused/are caused/

Complete sentences; end with period.

[bokan, 2015-06-09 15:09:13]

https://codereview.chromium.org/1146053009/diff/60001/content/public/common/c...
File content/public/common/content_switches.cc (right):

https://codereview.chromium.org/1146053009/diff/60001/content/public/common/c...
content/public/common/content_switches.cc:610: // and portrait mode (i.e.
Android) so the page should be rescaled to fit
On 2015/06/09 14:40:26, Avi wrote:
> s/are the caused/are caused/
> 
> Complete sentences; end with period.

Done.

[bokan, 2015-06-09 15:09:27]

The CQ bit was checked by bokan@chromium.org

[bokan, 2015-06-09 15:09:27]

The patchset sent to the CQ was uploaded after l-g-t-m from aelias@chromium.org,
kenrb@chromium.org, avi@chromium.org
Link to the patchset: https://codereview.chromium.org/1146053009/#ps80001
(title: "Fixed comment")

[commit-bot: I haz the power, 2015-06-09 15:10:17]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1146053009/80001

[commit-bot: I haz the power, 2015-06-09 16:22:45]

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

[commit-bot: I haz the power, 2015-06-09 16:22:47]

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

[bokan, 2015-06-09 16:50:05]

bokan@chromium.org changed reviewers:
+ asvitkine@chromium.org

[bokan, 2015-06-09 16:50:06]

+asvitkine@ for histograms.xml

[bokan, 2015-06-09 16:50:25]

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

[bokan, 2015-06-09 16:50:25]

The patchset sent to the CQ was uploaded after l-g-t-m from kenrb@chromium.org,
aelias@chromium.org, avi@chromium.org
Link to the patchset: https://codereview.chromium.org/1146053009/#ps100001
(title: "Added new about_flag to histograms.xml")

[commit-bot: I haz the power, 2015-06-09 16:51:16]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1146053009/100001

[Alexei Svitkine (slow), 2015-06-09 17:08:41]

lgtm

[commit-bot: I haz the power, 2015-06-09 17:56:59]

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

[commit-bot: I haz the power, 2015-06-09 17:57:00]

Dry run: This issue passed the CQ dry run.

[bokan, 2015-06-09 18:36:43]

The CQ bit was checked by bokan@chromium.org

[commit-bot: I haz the power, 2015-06-09 18:37:22]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1146053009/100001

[commit-bot: I haz the power, 2015-06-09 18:41:37]

Committed patchset #6 (id:100001)

[commit-bot: I haz the power, 2015-06-09 18:42:27]

Patchset 6 (id:??) landed as
https://crrev.com/9e55696155786e6e64045d594c5fc3720e979fd5
Cr-Commit-Position: refs/heads/master@{#333540}