Revert of Remove client_certs from SSLCertRequestInfo.

Revert of Remove client_certs from SSLCertRequestInfo. (patchset #4 id:60001 of https://codereview.chromium.org/2838243002/ )

Reason for revert:
Reverting in hopes of fixing 716594 . Will reland if it turns out to be another patch.

Original issue's description:
> Remove client_certs from SSLCertRequestInfo.
> 
> The client_certs aren't actually part of the certificate request, rather the client_certs member was used to store the list of matching certificates on the client side and pass them through to the certificate selector.
> Pass the list of certs through the relevant callbacks instead.
> 
> BUG=166642, 394131
> 
> Review-Url: https://codereview.chromium.org/2838243002
> Cr-Commit-Position: refs/heads/master@{#467901}
> Committed: https://chromium.googlesource.com/chromium/src/+/7ed243fc89fb72230c47f59742128add62ae1d83

TBR=davidben@chromium.org,sergeyu@chromium.org,lcwu@chromium.org,sgurun@chromium.org,pfeldman@chromium.org,emaxx@chromium.org,rsleevi@chromium.org,tedchoc@chromium.org,ellyjones@chromium.org,msw@chromium.org,dougsteed@chromium.org,ryanchung@chromium.org,mattm@chromium.org
# Not skipping CQ checks because original CL landed more than 1 days ago.
BUG=166642, 394131

[sky, 2017-05-01 19:27:33]

The CQ bit was checked by sky@chromium.org

[sky, 2017-05-01 19:27:34]

Created Revert of Remove client_certs from SSLCertRequestInfo.

[commit-bot: I haz the power, 2017-05-01 19:28:05]

CQ is trying da patch.

Follow status at:
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[mattm, 2017-05-01 19:58:39]

On 2017/05/01 19:28:05, commit-bot: I haz the power wrote:
> CQ is trying da patch.
> 
> Follow status at:
>
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

https://build.chromium.org/p/chromium.chromiumos/builders/Linux%20ChromiumOS%...
has the same failure at revision 467879, which is before 
https://codereview.chromium.org/2838243002 (467901)

[mattm, 2017-05-01 19:58:49]

The CQ bit was unchecked by mattm@chromium.org