Add metrics for style update time before FCP.

Add metrics for style update time before FCP.

BUG=666030
Committed: https://crrev.com/246860b48c9fcfca69448d7900f58cae13789a79
Cr-Commit-Position: refs/heads/master@{#436989}

[Charlie Harrison, 2016-11-28 16:19:14]

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

[commit-bot: I haz the power, 2016-11-28 16:19:32]

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

[Charlie Harrison, 2016-11-28 16:52:23]

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

[commit-bot: I haz the power, 2016-11-28 16:52:48]

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

[Charlie Harrison, 2016-11-28 18:00:02]

csharrison@chromium.org changed reviewers:
+ bmcquade@chromium.org, kouhei@chromium.org, mkwst@chromium.org,
rkaplow@chromium.org

[Charlie Harrison, 2016-11-28 18:00:03]

bmcquade: PTAL at everything

kouhei: PTAL at core/

rkaplow: PTAL at histograms.xml

mkwst: PTAL at page_load_metrics_messages

Thanks!

(cc timloh as FYI)

[rkaplow, 2016-11-28 18:07:03]

lgtm

[Bryan McQuade, 2016-11-28 18:30:53]

LGTM - just a request for one more histogram.

https://codereview.chromium.org/2533783003/diff/40001/chrome/browser/page_loa...
File
chrome/browser/page_load_metrics/observers/core_page_load_metrics_observer.cc
(right):

https://codereview.chromium.org/2533783003/diff/40001/chrome/browser/page_loa...
chrome/browser/page_load_metrics/observers/core_page_load_metrics_observer.cc:348:
if (timing.style_sheet_timing.update_style_duration_before_fcp) {
we discussed this in chat, but noting here as well:

in addition to having separate metrics for each, let's also add a single
PageLoad.CssTiming.ParseAndUpdate.BeforeFirstContentfulPaint that reports the
sum of both (in cases where at least one is set). that way  you can reason about
% of pages that get overall faster or slower in style time in an a/b trial.

[Charlie Harrison, 2016-11-28 18:57:36]

rkaplow: Note there is a new histogram logged in this CL since your l-g.

https://codereview.chromium.org/2533783003/diff/40001/chrome/browser/page_loa...
File
chrome/browser/page_load_metrics/observers/core_page_load_metrics_observer.cc
(right):

https://codereview.chromium.org/2533783003/diff/40001/chrome/browser/page_loa...
chrome/browser/page_load_metrics/observers/core_page_load_metrics_observer.cc:348:
if (timing.style_sheet_timing.update_style_duration_before_fcp) {
On 2016/11/28 18:30:52, Bryan McQuade wrote:
> we discussed this in chat, but noting here as well:
> 
> in addition to having separate metrics for each, let's also add a single
> PageLoad.CssTiming.ParseAndUpdate.BeforeFirstContentfulPaint that reports the
> sum of both (in cases where at least one is set). that way  you can reason
about
> % of pages that get overall faster or slower in style time in an a/b trial.

Done.

[Bryan McQuade, 2016-11-28 19:05:18]

Thanks! One more comment.

https://codereview.chromium.org/2533783003/diff/60001/chrome/browser/page_loa...
File
chrome/browser/page_load_metrics/observers/core_page_load_metrics_observer.cc
(right):

https://codereview.chromium.org/2533783003/diff/60001/chrome/browser/page_loa...
chrome/browser/page_load_metrics/observers/core_page_load_metrics_observer.cc:353:
if (timing.style_sheet_timing
I'd log this if either one is set, rather than requiring that both are set. That
way, if for instance you defer all update_style_duration until after FCP (and
thus that value is unset) you still report the total time spent before FCP for
that page.

[Charlie Harrison, 2016-11-28 19:10:11]

https://codereview.chromium.org/2533783003/diff/60001/chrome/browser/page_loa...
File
chrome/browser/page_load_metrics/observers/core_page_load_metrics_observer.cc
(right):

https://codereview.chromium.org/2533783003/diff/60001/chrome/browser/page_loa...
chrome/browser/page_load_metrics/observers/core_page_load_metrics_observer.cc:353:
if (timing.style_sheet_timing
On 2016/11/28 19:05:18, Bryan McQuade wrote:
> I'd log this if either one is set, rather than requiring that both are set.
That
> way, if for instance you defer all update_style_duration until after FCP (and
> thus that value is unset) you still report the total time spent before FCP for
> that page.

Done good catch.

[Charlie Harrison, 2016-11-28 19:18:20]

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

[commit-bot: I haz the power, 2016-11-28 19:18:54]

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

[Bryan McQuade, 2016-11-28 19:19:41]

LGTM, thx!

[commit-bot: I haz the power, 2016-11-28 22:00:09]

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

[commit-bot: I haz the power, 2016-11-28 22:00:10]

Dry run: This issue passed the CQ dry run.

[kouhei (in TOK), 2016-11-29 01:18:41]

lgtm

[Charlie Harrison, 2016-12-05 19:34:37]

mkwst friendly ping for trivial IPC change

[Mike West, 2016-12-07 14:50:53]

Trivial changes LGTM!

[Charlie Harrison, 2016-12-07 14:53:59]

Thanks!

[Charlie Harrison, 2016-12-07 14:54:03]

The CQ bit was checked by csharrison@chromium.org

[Charlie Harrison, 2016-12-07 14:54:03]

The patchset sent to the CQ was uploaded after l-g-t-m from rkaplow@chromium.org
Link to the patchset: https://codereview.chromium.org/2533783003/#ps100001
(title: "value_or(base::TimeDelta())")

[commit-bot: I haz the power, 2016-12-07 14:54:23]

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, 2016-12-07 17:19:55]

CQ is committing da patch.

Bot data: {"patchset_id": 100001, "attempt_start_ts": 1481122443275500,
"parent_rev": "ab9386a6102ff4de028fd8ffc3c451386506544b", "commit_rev":
"2573fe88bc53fe16af2316f2700b155890e5e810"}

[commit-bot: I haz the power, 2016-12-07 17:20:25]

Committed patchset #6 (id:100001)

[commit-bot: I haz the power, 2016-12-07 17:22:59]

Description was changed from

==========
Add metrics for style update time before FCP.

BUG=666030
==========

to

==========
Add metrics for style update time before FCP.

BUG=666030

Committed: https://crrev.com/246860b48c9fcfca69448d7900f58cae13789a79
Cr-Commit-Position: refs/heads/master@{#436989}
==========

[commit-bot: I haz the power, 2016-12-07 17:23:00]

Patchset 6 (id:??) landed as
https://crrev.com/246860b48c9fcfca69448d7900f58cae13789a79
Cr-Commit-Position: refs/heads/master@{#436989}