InstantExtended: record Instant NTP load times.

InstantExtended: record Instant NTP load times.

This uses the same histogram name as the existing NTP (Tab.NewTabOnload) which
should make it easy to see how it compares to the old load times.

BUG=325228
TESTED=manually, looking at about://histograms

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=243188

[samarth, 2013-12-16 23:58:16]

PTAL.

Thanks,
Samarth

[samarth, 2014-01-02 20:00:15]

ping?

[Jered, 2014-01-02 20:12:41]

Sorry missed this, quick question.

https://codereview.chromium.org/112453004/diff/1/chrome/browser/ui/search/sea...
File chrome/browser/ui/search/search_tab_helper.cc (right):

https://codereview.chromium.org/112453004/diff/1/chrome/browser/ui/search/sea...
chrome/browser/ui/search/search_tab_helper.cc:137:
core_tab_helper->set_new_tab_start_time(base::TimeTicks());
Why are you resetting the start time here?

[samarth, 2014-01-04 01:22:38]

https://codereview.chromium.org/112453004/diff/1/chrome/browser/ui/search/sea...
File chrome/browser/ui/search/search_tab_helper.cc (right):

https://codereview.chromium.org/112453004/diff/1/chrome/browser/ui/search/sea...
chrome/browser/ui/search/search_tab_helper.cc:137:
core_tab_helper->set_new_tab_start_time(base::TimeTicks());
On 2014/01/02 20:12:41, Jered wrote:
> Why are you resetting the start time here?

This is because not all code paths that open the NTP record the start time
(IIRC, only if you use ctrl+T or if you click on the new tab button).  And we
use the existence of a non-null start here to decide whether the start time was
recorded. So if we didn't clear here and then opened an NTP in the same tab
again by typing chrome://newtab, it would record the wrong time.

[Jered, 2014-01-06 14:05:58]

lgtm

[commit-bot: I haz the power, 2014-01-06 17:41:45]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/samarth@chromium.org/112453004/1

[commit-bot: I haz the power, 2014-01-06 22:33:21]

Change committed as 243188