Record the time to requestStart from the javascript timings API as part of the startup benchmark.

Record the time to requestStart from the javascript timings API as part of the startup benchmark.

BUG=413679
Committed: https://crrev.com/cedb7335ace6069cfb9f00961dc5da88c9c983d8
Cr-Commit-Position: refs/heads/master@{#297139}

[azarchs, 2014-09-17 12:53:44]

azarchs@chromium.org changed reviewers:
+ pasko@chromium.org

[azarchs, 2014-09-17 12:53:45]

This is the quick and simple approach to getting the first request benchmark.

[pasko, 2014-09-17 13:25:09]

https://codereview.chromium.org/546213005/diff/20001/tools/perf/metrics/start...
File tools/perf/metrics/startup_metric.py (right):

https://codereview.chromium.org/546213005/diff/20001/tools/perf/metrics/start...
tools/perf/metrics/startup_metric.py:70: raise Exception("requestStart not in
window performance timings")
this would abort execution of all tests. Even if all browsers able to run with
telemetry have requestStart, still scary.

https://codereview.chromium.org/546213005/diff/20001/tools/perf/metrics/start...
tools/perf/metrics/startup_metric.py:98: results.current_page,
'foreground_tab_request_start', 'ms',
why absolute value and not the relative one? LoadingMetric reports it as
relative to navigationStart. I am not sure in which circumstances we use each
metric though.

[azarchs, 2014-09-17 13:57:17]

https://codereview.chromium.org/546213005/diff/20001/tools/perf/metrics/start...
File tools/perf/metrics/startup_metric.py (right):

https://codereview.chromium.org/546213005/diff/20001/tools/perf/metrics/start...
tools/perf/metrics/startup_metric.py:70: raise Exception("requestStart not in
window performance timings")
On 2014/09/17 13:25:08, pasko wrote:
> this would abort execution of all tests. Even if all browsers able to run with
> telemetry have requestStart, still scary.

Done.

https://codereview.chromium.org/546213005/diff/20001/tools/perf/metrics/start...
tools/perf/metrics/startup_metric.py:98: results.current_page,
'foreground_tab_request_start', 'ms',
On 2014/09/17 13:25:08, pasko wrote:
> why absolute value and not the relative one? LoadingMetric reports it as
> relative to navigationStart. I am not sure in which circumstances we use each
> metric though.

The value reported here is relative to the process start. 
window.performance.timing.requestStart is an absolute time from 1970.

[pasko, 2014-09-17 16:15:42]

lgtm

[azarchs, 2014-09-17 16:19:52]

azarchs@chromium.org changed reviewers:
+ epenner@chromium.org

[azarchs, 2014-09-17 16:19:57]

Thanks, now I need someone for owners approval.  I hope you don't mind being
that someone, Eric.

[epenner, 2014-09-22 19:08:46]

On 2014/09/17 16:19:57, azarchs wrote:
> Thanks, now I need someone for owners approval.  I hope you don't mind being
> that someone, Eric.

LGTM rubber-stamp. The code looks fine but I'm assuming the approach was agreed
upon etc. (looks like it on the bug).

[azarchs, 2014-09-29 04:07:45]

The CQ bit was checked by azarchs@chromium.org

[commit-bot: I haz the power, 2014-09-29 04:08:53]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/546213005/40001

[commit-bot: I haz the power, 2014-09-29 05:06:38]

Committed patchset #3 (id:40001) as 201680b8cc6a2a916a64d2abde860d711d0aab03

[commit-bot: I haz the power, 2014-09-29 05:07:14]

Patchset 3 (id:??) landed as
https://crrev.com/cedb7335ace6069cfb9f00961dc5da88c9c983d8
Cr-Commit-Position: refs/heads/master@{#297139}