Add recording of when a prerender actually starts to prerender histograms.

Add recording of when a prerender actually starts to prerender histograms. This allows us to remove any trivially rejected prerenders from some counts.

BUG=105733
Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=112708

[cbentzel, 2011-12-01 19:03:50]

LGTM

[commit-bot: I haz the power, 2011-12-01 23:10:05]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/dominich@chromium.org/8776011/1

[commit-bot: I haz the power, 2011-12-02 00:35:13]

The commit queue went berserk retrying too often for a
seemingly flaky test. Builder is mac_rel, revision is 112568, job name
was 8776011-1 (previous was lost) (previous was lost) (previous was lost)
(previous was lost).

[commit-bot: I haz the power, 2011-12-02 00:37:09]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/dominich@chromium.org/8776011/1

[commit-bot: I haz the power, 2011-12-02 03:00:08]

Try job failure for 8776011-1 (previous was lost) (retry) on win_rel for step
"browser_tests".
It's a second try, previously, step "browser_tests" failed.
http://build.chromium.org/p/tryserver.chromium/buildstatus?builder=win_rel&nu...

[commit-bot: I haz the power, 2011-12-02 14:35:54]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/dominich@chromium.org/8776011/1

[commit-bot: I haz the power, 2011-12-02 16:00:39]

Change committed as 112708