Revert of Make ONCCertificateImporter async.

Revert of Make ONCCertificateImporter async. (patchset #1 id:1 of https://codereview.chromium.org/582413002/)

Reason for revert:
Use-after-free.
https://code.google.com/p/chromium/issues/detail?id=415916

Original issue's description:
> Make ONCCertificateImporter async.
>
> This prepares for the new CertDatabase keyed service, which will have stricter threading restrictions. https://codereview.chromium.org/419013003/
> Before, ONCCertificateImporter accessed the NSSCertDatabase from the UI thread and blocked on certificate store operations.
> Now, the import itself is asychronous and calls back on completion.
>
> While there, this also removes the GMock of the importer.
>
> This is a reland of f08303014b165f6013fe33198cd798ebd9a4e925
>   refs/heads/master@{#295534}
> with the fixed destruction order in ONCCertificateImporterImplTest.
>
> The fix was reviewed in
>   https://codereview.chromium.org/589443002/
>
> TBR=eroman@chromium.org
> BUG=413219
>
> Committed: https://crrev.com/3b4ba221657f6b27e2156818bc445c885d87fc0e
> Cr-Commit-Position: refs/heads/master@{#295687}

TBR=joaodasilva@chromium.org,eroman@chromium.org,pneubeck@chromium.org
NOTREECHECKS=true
NOTRY=true
BUG=413219
Committed: https://crrev.com/3d9825c9ceda48206c96911e07b862609d19078f
Cr-Commit-Position: refs/heads/master@{#295702}

[eugenis, 2014-09-19 14:30:52]

Created Revert of Make ONCCertificateImporter async.

[commit-bot: I haz the power, 2014-09-19 14:31:33]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/584923002/1

[commit-bot: I haz the power, 2014-09-19 14:32:20]

Committed patchset #1 (id:1) as bbde9050bca061f9297a4e6d36a14a9d1f8245cc

[commit-bot: I haz the power, 2014-09-19 14:33:00]

Patchset 1 (id:??) landed as
https://crrev.com/3d9825c9ceda48206c96911e07b862609d19078f
Cr-Commit-Position: refs/heads/master@{#295702}