Revert of Revert of Don't deref stale AutofillMetrics pointer in AutofillCCInfoBarDelegate

Revert of Revert of Don't deref stale AutofillMetrics pointer in AutofillCCInfoBarDelegate (patchset #1 id:1 of https://codereview.chromium.org/790543002/)

Reason for revert:
Re-landing, revert didn't fix Win7 bots..

Original issue's description:
> Revert of Don't deref stale AutofillMetrics pointer in AutofillCCInfoBarDelegate (patchset #2 id:20001 of https://codereview.chromium.org/780423002/)
>
> Reason for revert:
> Suspected cause of flakines on Win7-bots, see http://crbug.com/440060 for details.
>
> Original issue's description:
> > Don't deref stale AutofillMetrics pointer in AutofillCCInfoBarDelegate
> >
> > It was only by luck that this used to work. After a recent refactoring, the destruction order changed and the AutofillMetrics object no longer outlasts the infobar. AutofillMetrics doesn't need to be an instance object; make the relevant function a static instead.
> >
> > TBR=sgurun@chromium.org
> > BUG=439551, 439620
> >
> > Committed: https://crrev.com/19ece1e4af5207b92c2152395dfccca1683504e1
> > Cr-Commit-Position: refs/heads/master@{#307128}
>
> TBR=isherman@chromium.org,pkasting@chromium.org,estade@chromium.org
> NOTREECHECKS=true
> NOTRY=true
> BUG=439551, 439620
>
> Committed: https://crrev.com/051aca46ed1dec4f040c9a3d7dac2af60df2db6c
> Cr-Commit-Position: refs/heads/master@{#307303}

TBR=isherman@chromium.org,pkasting@chromium.org,estade@chromium.org
NOTREECHECKS=true
NOTRY=true
BUG=439551, 439620, 440060
Committed: https://crrev.com/ce7cfee334855215412460f91fd4d0f29b5e4afb
Cr-Commit-Position: refs/heads/master@{#307345}

[gab, 2014-12-08 21:50:44]

Created Revert of Revert of Don't deref stale AutofillMetrics pointer in
AutofillCCInfoBarDelegate

[gab, 2014-12-08 21:51:01]

The CQ bit was checked by gab@chromium.org

[commit-bot: I haz the power, 2014-12-08 21:52:07]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/782353002/1

[commit-bot: I haz the power, 2014-12-08 21:54:16]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2014-12-08 21:55:02]

Patchset 1 (id:??) landed as
https://crrev.com/ce7cfee334855215412460f91fd4d0f29b5e4afb
Cr-Commit-Position: refs/heads/master@{#307345}