Add histograms for time to parse start for service worker controlled pages.

Add histograms for time to parse start for service worker controlled pages.

Service worker controlled pages should drive time to parse start down to near
zero. This change allows us to track the actual latency.

Additionally, this will allow us to improve the service worker stats UMA, where
we currently compute the percentage of page loads controlled by SW using UMA
sourced from different parts of the code in numerator and denominator.

BUG=684561
Review-Url: https://codereview.chromium.org/2651883006
Cr-Commit-Position: refs/heads/master@{#446838}
Committed: https://chromium.googlesource.com/chromium/src/+/b9c7574d2f2d7baaf78d42c5db8068fed0081145

[Bryan McQuade, 2017-01-24 15:07:32]

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

[commit-bot: I haz the power, 2017-01-24 15:07:44]

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, 2017-01-24 15:11:59]

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

[commit-bot: I haz the power, 2017-01-24 15:12:00]

Dry run: Try jobs failed on following builders:
  android_arm64_dbg_recipe on master.tryserver.chromium.android (JOB_FAILED,
https://build.chromium.org/p/tryserver.chromium.android/builders/android_arm6...)
  android_clang_dbg_recipe on master.tryserver.chromium.android (JOB_FAILED,
https://build.chromium.org/p/tryserver.chromium.android/builders/android_clan...)
  cast_shell_linux on master.tryserver.chromium.linux (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.linux/builders/cast_shell_linu...)
  chromeos_amd64-generic_chromium_compile_only_ng on
master.tryserver.chromium.linux (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.linux/builders/chromeos_amd64-...)

[Bryan McQuade, 2017-01-24 15:12:04]

Description was changed from

==========
Add histograms for time to parse start for service worker controlled pages.

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

to

==========
Add histograms for time to parse start for service worker controlled pages.

Service worker controlled pages should drive time to parse start down to near
zero. This change allows us to track the actual latency.

Additionally, this will allow us to improve the service worker stats UMA, where
we currently compute the percentage of page loads controlled by SW using UMA
sourced from different parts of the code in numerator and denominator.

BUG=684561
==========

[Bryan McQuade, 2017-01-24 21:06:20]

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

[commit-bot: I haz the power, 2017-01-24 21:06:53]

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, 2017-01-24 21:27:32]

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

[commit-bot: I haz the power, 2017-01-24 21:27:32]

Dry run: Try jobs failed on following builders:
  android_compile_dbg on master.tryserver.chromium.android (JOB_FAILED,
https://build.chromium.org/p/tryserver.chromium.android/builders/android_comp...)

[Bryan McQuade, 2017-01-25 16:21:03]

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

[commit-bot: I haz the power, 2017-01-25 16:21:25]

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, 2017-01-25 18:00:26]

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

[commit-bot: I haz the power, 2017-01-25 18:00:28]

Dry run: Try jobs failed on following builders:
  linux_android_rel_ng on master.tryserver.chromium.android (JOB_FAILED,
https://build.chromium.org/p/tryserver.chromium.android/builders/linux_androi...)

[Bryan McQuade, 2017-01-26 23:56:16]

bmcquade@chromium.org changed reviewers:
+ holte@chromium.org, kenjibaheux@chromium.org

[Bryan McQuade, 2017-01-26 23:56:32]

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

[Bryan McQuade, 2017-01-26 23:57:03]

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

[Bryan McQuade, 2017-01-26 23:57:04]

csharrison, PTAL for observer changes
holte, PTAL for histograms.xml

thanks!

[Bryan McQuade, 2017-01-26 23:58:43]

csharrison, one note: though we've mostly stopped using background histograms,
we do need one in this case, as one of the key service worker metrics computes
page loads w/ a service worker, among all page loads that start parsing (both fg
and bg). we want fg to understand performance of foreground pages, and bg to
know the total number of pages (fg+bg).

[Charlie Harrison, 2017-01-27 00:25:44]

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

[Charlie Harrison, 2017-01-27 00:25:45]

That's fine by me

[Steven Holte, 2017-01-27 20:52:37]

histograms lgtm

[Charlie Harrison, 2017-01-27 21:03:18]

LGTM

[Bryan McQuade, 2017-01-27 22:17:26]

The CQ bit was checked by bmcquade@chromium.org

[commit-bot: I haz the power, 2017-01-27 22:18:36]

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, 2017-01-27 23:51:12]

CQ is committing da patch.

Bot data: {"patchset_id": 40001, "attempt_start_ts": 1485555446090320,
"parent_rev": "bc96e9c35a0807bb6b55d416b53b10f2dc2cc3a2", "commit_rev":
"b9c7574d2f2d7baaf78d42c5db8068fed0081145"}

[commit-bot: I haz the power, 2017-01-27 23:51:46]

Description was changed from

==========
Add histograms for time to parse start for service worker controlled pages.

Service worker controlled pages should drive time to parse start down to near
zero. This change allows us to track the actual latency.

Additionally, this will allow us to improve the service worker stats UMA, where
we currently compute the percentage of page loads controlled by SW using UMA
sourced from different parts of the code in numerator and denominator.

BUG=684561
==========

to

==========
Add histograms for time to parse start for service worker controlled pages.

Service worker controlled pages should drive time to parse start down to near
zero. This change allows us to track the actual latency.

Additionally, this will allow us to improve the service worker stats UMA, where
we currently compute the percentage of page loads controlled by SW using UMA
sourced from different parts of the code in numerator and denominator.

BUG=684561

Review-Url: https://codereview.chromium.org/2651883006
Cr-Commit-Position: refs/heads/master@{#446838}
Committed:
https://chromium.googlesource.com/chromium/src/+/b9c7574d2f2d7baaf78d42c5db80...
==========

[commit-bot: I haz the power, 2017-01-27 23:51:47]

Committed patchset #3 (id:40001) as
https://chromium.googlesource.com/chromium/src/+/b9c7574d2f2d7baaf78d42c5db80...

[Nico, 2017-01-28 16:57:48]

Looks like this broke tests on
https://build.chromium.org/p/chromium.win/builders/Win7%20Tests%20%28dbg%29%2...
:

https://build.chromium.org/p/chromium.win/builders/Win7%20Tests%20%28dbg%29%2...

[ RUN      ]
ServiceWorkerPageLoadMetricsObserverTest.WithServiceWorkerBackground
c:\c\win\srcase	est\histogram_tester.cc(72): error: Value of: 0
Expected: count
Which is: 1
Histogram
"PageLoad.Clients.ServiceWorker.ParseTiming.NavigationToParseStart.Background"
does not exist.
[  FAILED  ]
ServiceWorkerPageLoadMetricsObserverTest.WithServiceWorkerBackground (357 ms)

I'd revert, but rietveld says "file too large" – guess histogram.xml changes
can't be reverted through rietveld any longer :-( Please revert manually, and
then fix.

[Bryan McQuade, 2017-01-29 22:39:00]

On 2017/01/28 at 16:57:48, thakis wrote:
> Looks like this broke tests on
https://build.chromium.org/p/chromium.win/builders/Win7%20Tests%20%28dbg%29%2...
:
> 
>
https://build.chromium.org/p/chromium.win/builders/Win7%20Tests%20%28dbg%29%2...
> 
> [ RUN      ]
ServiceWorkerPageLoadMetricsObserverTest.WithServiceWorkerBackground
> c:\c\win\srcase	est\histogram_tester.cc(72): error: Value of: 0
> Expected: count
> Which is: 1
> Histogram
"PageLoad.Clients.ServiceWorker.ParseTiming.NavigationToParseStart.Background"
does not exist.
> [  FAILED  ]
ServiceWorkerPageLoadMetricsObserverTest.WithServiceWorkerBackground (357 ms)
> 
> I'd revert, but rietveld says "file too large" – guess histogram.xml changes
can't be reverted through rietveld any longer :-( Please revert manually, and
then fix.

Thanks. I'm working on landing a change to disable the single failing assertion
for the time being. Should land shortly.