Fix flakiness in page_load_metrics_browser_test

Fix flakiness in page_load_metrics_browser_test

This is a speculative fix for test failures that happen
because histograms are not updated.

This CL catches the case where the IPC updating the
histogram would still be in flight when the histograms
are checked.
If the histograms are missing, there is now a mechanism
to wait for the IPC to arrive.

BUG=657022
Committed: https://crrev.com/2ce641d6fa80fc0a9ea2fe1484f6040224e2a6a3
Cr-Commit-Position: refs/heads/master@{#428039}

[droger, 2016-10-25 12:36:17]

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

[commit-bot: I haz the power, 2016-10-25 12:36:36]

Dry run: 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, 2016-10-25 13:16:16]

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

[commit-bot: I haz the power, 2016-10-25 13:16:17]

Dry run: This issue passed the CQ dry run.

[droger, 2016-10-25 13:25:57]

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

[droger, 2016-10-25 13:26:11]

Patchset #1 (id:1) has been deleted

[commit-bot: I haz the power, 2016-10-25 13:26:19]

Dry run: CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[droger, 2016-10-25 13:30:14]

Description was changed from

==========
Fix flakiness in page_load_metrics_browser_test
==========

to

==========
Fix flakiness in page_load_metrics_browser_test

This is a speculative fix for test failures.

The failures happen because histograms are not updated.
This CL catches the case where the IPC updating the
histogram would still be in flight when the histograms
are checked.

If the histograms are missing, there is now a mechanism
to wait for the IPC to arrive.

BUG=657022
==========

[droger, 2016-10-25 13:30:48]

Description was changed from

==========
Fix flakiness in page_load_metrics_browser_test

This is a speculative fix for test failures.

The failures happen because histograms are not updated.
This CL catches the case where the IPC updating the
histogram would still be in flight when the histograms
are checked.

If the histograms are missing, there is now a mechanism
to wait for the IPC to arrive.

BUG=657022
==========

to

==========
Fix flakiness in page_load_metrics_browser_test

This is a speculative fix for test failures that happen
because histograms are not updated.

This CL catches the case where the IPC updating the
histogram would still be in flight when the histograms
are checked.
If the histograms are missing, there is now a mechanism
to wait for the IPC to arrive.

BUG=657022
==========

[droger, 2016-10-25 13:35:15]

droger@chromium.org changed reviewers:
+ bmcquade@chromium.org, pasko@chromium.org

[droger, 2016-10-25 13:35:16]

I could somewhat reproduce the failures by increasing/adding delays in
chrome/renderer/page_load_metrics/page_timing_metrics_sender.cc, but I'm not
sure this is really conclusive.

Since this fix is speculative, we can possibly revert it if it turns out it does
not work.

[commit-bot: I haz the power, 2016-10-25 13:59:57]

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

[commit-bot: I haz the power, 2016-10-25 13:59:58]

Dry run: This issue passed the CQ dry run.

[Bryan McQuade, 2016-10-25 15:14:41]

bmcquade@chromium.org changed reviewers:
+ csharrison@chromium.org

[pasko, 2016-10-25 15:25:14]

non-owner lgtm

[Bryan McQuade, 2016-10-25 16:27:30]

On 2016/10/25 at 15:25:14, pasko wrote:
> non-owner lgtm

Thank you for this change! I agree that espeically as we move to mojoification,
we'll no longer be able to depend on order of processing of cross process
messages, so adding code to explicitly wait for the timing update to be
processed is a valuable addition.

High level this change looks very good. I will take a little more time to go
over the change and send feedback. Will try to have comments back to you in the
next few days.

Thanks again!

[Bryan McQuade, 2016-10-26 18:26:02]

LGTM, thank you!

[droger, 2016-10-27 15:26:52]

Thanks.

I will monitor the flakiness dashboard and report the results.

[droger, 2016-10-27 15:26:57]

The CQ bit was checked by droger@chromium.org

[commit-bot: I haz the power, 2016-10-27 15:27:12]

CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[pasko, 2016-10-27 15:29:24]

On 2016/10/27 15:26:52, droger wrote:
> Thanks.
> 
> I will monitor the flakiness dashboard and report the results.

Note: the flakiness dashboard is currently not responding:
https://bugs.chromium.org/p/chromium/issues/detail?id=659952

[commit-bot: I haz the power, 2016-10-27 16:12:49]

Description was changed from

==========
Fix flakiness in page_load_metrics_browser_test

This is a speculative fix for test failures that happen
because histograms are not updated.

This CL catches the case where the IPC updating the
histogram would still be in flight when the histograms
are checked.
If the histograms are missing, there is now a mechanism
to wait for the IPC to arrive.

BUG=657022
==========

to

==========
Fix flakiness in page_load_metrics_browser_test

This is a speculative fix for test failures that happen
because histograms are not updated.

This CL catches the case where the IPC updating the
histogram would still be in flight when the histograms
are checked.
If the histograms are missing, there is now a mechanism
to wait for the IPC to arrive.

BUG=657022
==========

[commit-bot: I haz the power, 2016-10-27 16:12:50]

Committed patchset #2 (id:40001)

[commit-bot: I haz the power, 2016-10-27 16:29:36]

Description was changed from

==========
Fix flakiness in page_load_metrics_browser_test

This is a speculative fix for test failures that happen
because histograms are not updated.

This CL catches the case where the IPC updating the
histogram would still be in flight when the histograms
are checked.
If the histograms are missing, there is now a mechanism
to wait for the IPC to arrive.

BUG=657022
==========

to

==========
Fix flakiness in page_load_metrics_browser_test

This is a speculative fix for test failures that happen
because histograms are not updated.

This CL catches the case where the IPC updating the
histogram would still be in flight when the histograms
are checked.
If the histograms are missing, there is now a mechanism
to wait for the IPC to arrive.

BUG=657022

Committed: https://crrev.com/2ce641d6fa80fc0a9ea2fe1484f6040224e2a6a3
Cr-Commit-Position: refs/heads/master@{#428039}
==========

[commit-bot: I haz the power, 2016-10-27 16:29:37]

Patchset 2 (id:??) landed as
https://crrev.com/2ce641d6fa80fc0a9ea2fe1484f6040224e2a6a3
Cr-Commit-Position: refs/heads/master@{#428039}