Put STHSet component behind a base::Feature.

Put STHSet component behind a base::Feature.

Keeps its default state as enabled, as before, but this
lets us experiment with turning it off experimentally to
see whether it may be causing a suspected startup
regression.

BUG=626676
Committed: https://crrev.com/6cc7584e55ab69b8a3454f1054fcf982f4a2584a
Cr-Commit-Position: refs/heads/master@{#404457}

[Alexei Svitkine (slow), 2016-07-08 15:25:35]

Description was changed from

==========
Put STHSet component behind a base::Feature.

Keeps its default state as enabled, as before, but this
lets us experiment with turning it off experimentally to
see whether it may be causing a suspected startup
regression.

BUG=
==========

to

==========
Put STHSet component behind a base::Feature.

Keeps its default state as enabled, as before, but this
lets us experiment with turning it off experimentally to
see whether it may be causing a suspected startup
regression.

BUG=626676
==========

[Alexei Svitkine (slow), 2016-07-08 15:26:02]

Description was changed from

==========
Put STHSet component behind a base::Feature.

Keeps its default state as enabled, as before, but this
lets us experiment with turning it off experimentally to
see whether it may be causing a suspected startup
regression.

BUG=626676
==========

to

==========
Put STHSet component behind a base::Feature.

Keeps its default state as enabled, as before, but this
lets us experiment with turning it off experimentally to
see whether it may be causing a suspected startup
regression.

Note: I confirmed with eranm@ that this is the right
way to do disable the component.

BUG=626676
==========

[Alexei Svitkine (slow), 2016-07-08 15:27:22]

asvitkine@chromium.org changed reviewers:
+ eranm@chromium.org, rkaplow@chromium.org

[Alexei Svitkine (slow), 2016-07-08 15:33:07]

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

[Alexei Svitkine (slow), 2016-07-08 15:33:08]

+thestig for chrome/ OWNERS as well

[Alexei Svitkine (slow), 2016-07-08 15:33:32]

Description was changed from

==========
Put STHSet component behind a base::Feature.

Keeps its default state as enabled, as before, but this
lets us experiment with turning it off experimentally to
see whether it may be causing a suspected startup
regression.

Note: I confirmed with eranm@ that this is the right
way to do disable the component.

BUG=626676
==========

to

==========
Put STHSet component behind a base::Feature.

Keeps its default state as enabled, as before, but this
lets us experiment with turning it off experimentally to
see whether it may be causing a suspected startup
regression.

BUG=626676
==========

[Eran Messeri, 2016-07-08 15:39:36]

lgtm

https://codereview.chromium.org/2131233002/diff/1/chrome/browser/chrome_brows...
File chrome/browser/chrome_browser_main.cc (right):

https://codereview.chromium.org/2131233002/diff/1/chrome/browser/chrome_brows...
chrome/browser/chrome_browser_main.cc:500: if
(base::FeatureList::IsEnabled(features::kSTHSetComponent)) {
Please document the experiment / link to a bug.

[Alexei Svitkine (slow), 2016-07-08 15:42:15]

https://codereview.chromium.org/2131233002/diff/1/chrome/browser/chrome_brows...
File chrome/browser/chrome_browser_main.cc (right):

https://codereview.chromium.org/2131233002/diff/1/chrome/browser/chrome_brows...
chrome/browser/chrome_browser_main.cc:500: if
(base::FeatureList::IsEnabled(features::kSTHSetComponent)) {
On 2016/07/08 15:39:36, Eran Messeri wrote:
> Please document the experiment / link to a bug.

Done.

[rkaplow, 2016-07-08 15:45:07]

lgtm

[Alexei Svitkine (slow), 2016-07-08 16:27:07]

Confirmed locally that this works as expected by looking at logging from
sth_set_component_installer.cc and seeing the logs from there by default and
then not seeing them when Chrome is started with:
--disable-features=STHSetComponent

(In my build, with the feature on, I see the loop iterate over 10 files.)

[Lei Zhang, 2016-07-08 17:17:17]

rs lgtm

[Alexei Svitkine (slow), 2016-07-08 17:26:34]

The CQ bit was checked by asvitkine@chromium.org

[Alexei Svitkine (slow), 2016-07-08 17:26:34]

The patchset sent to the CQ was uploaded after l-g-t-m from eranm@chromium.org
Link to the patchset: https://codereview.chromium.org/2131233002/#ps20001
(title: "Add a comment.")

[commit-bot: I haz the power, 2016-07-08 17:27:03]

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, 2016-07-08 19:15:13]

Description was changed from

==========
Put STHSet component behind a base::Feature.

Keeps its default state as enabled, as before, but this
lets us experiment with turning it off experimentally to
see whether it may be causing a suspected startup
regression.

BUG=626676
==========

to

==========
Put STHSet component behind a base::Feature.

Keeps its default state as enabled, as before, but this
lets us experiment with turning it off experimentally to
see whether it may be causing a suspected startup
regression.

BUG=626676
==========

[commit-bot: I haz the power, 2016-07-08 19:15:15]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2016-07-08 19:18:27]

Description was changed from

==========
Put STHSet component behind a base::Feature.

Keeps its default state as enabled, as before, but this
lets us experiment with turning it off experimentally to
see whether it may be causing a suspected startup
regression.

BUG=626676
==========

to

==========
Put STHSet component behind a base::Feature.

Keeps its default state as enabled, as before, but this
lets us experiment with turning it off experimentally to
see whether it may be causing a suspected startup
regression.

BUG=626676

Committed: https://crrev.com/6cc7584e55ab69b8a3454f1054fcf982f4a2584a
Cr-Commit-Position: refs/heads/master@{#404457}
==========

[commit-bot: I haz the power, 2016-07-08 19:18:29]

Patchset 2 (id:??) landed as
https://crrev.com/6cc7584e55ab69b8a3454f1054fcf982f4a2584a
Cr-Commit-Position: refs/heads/master@{#404457}