[Extensions] Fix crash in chrome://extensions metrics

[Extensions] Fix crash in chrome://extensions metrics

DidStartProvisionalLoadInFrame() is apparently not guaranteed to be
called before DocumentLoadedInFrame() or
DocumentOnLoadCompletedInMainFrame(). Because of this, the timer was
sometimes uninitialized. Handle this gracefully.

BUG=647272
Committed: https://crrev.com/d6e72e27f3a4d1d008cdd16e765d3fe6de482ff4
Cr-Commit-Position: refs/heads/master@{#419629}

[Devlin, 2016-09-19 21:06:12]

rdevlin.cronin@chromium.org changed reviewers:
+ dbeam@chromium.org

[Devlin, 2016-09-19 21:06:13]

Dan, mind taking a quick look?

[Dan Beam, 2016-09-19 21:08:05]

lgtm

[Devlin, 2016-09-19 21:24:55]

The CQ bit was checked by rdevlin.cronin@chromium.org

[commit-bot: I haz the power, 2016-09-19 21:25:32]

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, 2016-09-20 00:26:56]

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

[commit-bot: I haz the power, 2016-09-20 00:26:57]

Try jobs failed on following builders:
  mac_chromium_rel_ng on master.tryserver.chromium.mac (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.mac/builders/mac_chromium_rel_...)

[Devlin, 2016-09-20 00:30:37]

The CQ bit was checked by rdevlin.cronin@chromium.org

[commit-bot: I haz the power, 2016-09-20 00:31:29]

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, 2016-09-20 01:36:24]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2016-09-20 01:41:11]

Description was changed from

==========
[Extensions] Fix crash in chrome://extensions metrics

DidStartProvisionalLoadInFrame() is apparently not guaranteed to be
called before DocumentLoadedInFrame() or
DocumentOnLoadCompletedInMainFrame(). Because of this, the timer was
sometimes uninitialized. Handle this gracefully.

BUG=647272
==========

to

==========
[Extensions] Fix crash in chrome://extensions metrics

DidStartProvisionalLoadInFrame() is apparently not guaranteed to be
called before DocumentLoadedInFrame() or
DocumentOnLoadCompletedInMainFrame(). Because of this, the timer was
sometimes uninitialized. Handle this gracefully.

BUG=647272

Committed: https://crrev.com/d6e72e27f3a4d1d008cdd16e765d3fe6de482ff4
Cr-Commit-Position: refs/heads/master@{#419629}
==========

[commit-bot: I haz the power, 2016-09-20 01:41:12]

Patchset 1 (id:??) landed as
https://crrev.com/d6e72e27f3a4d1d008cdd16e765d3fe6de482ff4
Cr-Commit-Position: refs/heads/master@{#419629}