Even more instrumentation to diagnose an Android render crash.

Even more instrumentation to diagnose an Android render crash.

We're seeing renderers receiving IPCs to activate a trial to
a different state than what was specified on the command line.
This CL expands previously added instrumentation to detect if
this is happening via separate FieldTrialList instances by
also keeping a copy of the seen states between instances.

Note: While the locking here is done through the lock on the
FieldTrialList instance, this is safe to do because FieldTrialList
has a check to ensure there is only a single FieldTrialList
instance at a given time, so the single lock is sufficient.

BUG=359406
Committed: https://crrev.com/adc6a3f5593b054dcb114d54c8a6486536001e02
Cr-Commit-Position: refs/heads/master@{#387702}

[Alexei Svitkine (slow), 2016-04-15 18:58:43]

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

[Alexei Svitkine (slow), 2016-04-15 18:58:44]

Still chasing that elusive Android renderer crash. :(

Nico, mind reviewing?

[Nico, 2016-04-15 19:00:31]

lgtm

https://codereview.chromium.org/1897493002/diff/1/base/metrics/field_trial.cc
File base/metrics/field_trial.cc (right):

https://codereview.chromium.org/1897493002/diff/1/base/metrics/field_trial.cc...
base/metrics/field_trial.cc:644: if (g_use_global_check_states) {
should this block have a comment too?

[Alexei Svitkine (slow), 2016-04-15 20:28:46]

https://codereview.chromium.org/1897493002/diff/1/base/metrics/field_trial.cc
File base/metrics/field_trial.cc (right):

https://codereview.chromium.org/1897493002/diff/1/base/metrics/field_trial.cc...
base/metrics/field_trial.cc:644: if (g_use_global_check_states) {
On 2016/04/15 19:00:31, Nico wrote:
> should this block have a comment too?

Done.

[Alexei Svitkine (slow), 2016-04-15 20:28:49]

The CQ bit was checked by asvitkine@chromium.org

[Alexei Svitkine (slow), 2016-04-15 20:28:49]

The patchset sent to the CQ was uploaded after l-g-t-m from thakis@chromium.org
Link to the patchset: https://codereview.chromium.org/1897493002/#ps20001
(title: "Add more comments.")

[commit-bot: I haz the power, 2016-04-15 20:29:17]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1897493002/20001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1897493002/20001

[commit-bot: I haz the power, 2016-04-15 21:33:44]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2016-04-15 21:35:28]

Description was changed from

==========
Even more instrumentation to diagnose an Android render crash.

We're seeing renderers receiving IPCs to activate a trial to
a different state than what was specified on the command line.
This CL expands previously added instrumentation to detect if
this is happening via separate FieldTrialList instances by
also keeping a copy of the seen states between instances.

Note: While the locking here is done through the lock on the
FieldTrialList instance, this is safe to do because FieldTrialList
has a check to ensure there is only a single FieldTrialList
instance at a given time, so the single lock is sufficient.

BUG=359406
==========

to

==========
Even more instrumentation to diagnose an Android render crash.

We're seeing renderers receiving IPCs to activate a trial to
a different state than what was specified on the command line.
This CL expands previously added instrumentation to detect if
this is happening via separate FieldTrialList instances by
also keeping a copy of the seen states between instances.

Note: While the locking here is done through the lock on the
FieldTrialList instance, this is safe to do because FieldTrialList
has a check to ensure there is only a single FieldTrialList
instance at a given time, so the single lock is sufficient.

BUG=359406

Committed: https://crrev.com/adc6a3f5593b054dcb114d54c8a6486536001e02
Cr-Commit-Position: refs/heads/master@{#387702}
==========

[commit-bot: I haz the power, 2016-04-15 21:35:29]

Patchset 2 (id:??) landed as
https://crrev.com/adc6a3f5593b054dcb114d54c8a6486536001e02
Cr-Commit-Position: refs/heads/master@{#387702}