Revert of Move SecurityLevel into a class of its own

Revert of Move SecurityLevel into a class of its own (patchset #16 id:370001 of https://codereview.chromium.org/1123943002/)

Reason for revert:
Downstream build broken by this change because of forgotten JNI method registration. I need to register the JNI method before relanding.

Original issue's description:
> Move SecurityLevel into a class of its own
>
> This CL moves |GetSecurityLevelForWebContents| and the |SecurityLevel|
> enum into a class of their own: |ConnectionSecurityHelper| in
> //chrome/browser/ssl (since it is applying Chrome-specific security
> policy to determine the security level of a page).
>
> Later, we will use the new |ConnectionSecurityHelper| class to compute a
> security level for a page to send to the DevTools Security
> panel. Specifically, we need to be able to calculate the security level
> for a given page, not just the WebContents for the active tab.
>
> BUG=484392
>
> Committed: https://crrev.com/ca7c0a3374c21ab10c821f4f3a890afc79182acf
> Cr-Commit-Position: refs/heads/master@{#329591}

TBR=felt@chromium.org,pkasting@chromium.org,rsleevi@chromium.org,bauerb@chromium.org,sky@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=484392
Committed: https://crrev.com/4e9c2774d004a1fce0b1f572398e3b0c9e3337f7
Cr-Commit-Position: refs/heads/master@{#329654}

[estark, 2015-05-13 16:33:39]

Created Revert of Move SecurityLevel into a class of its own

[commit-bot: I haz the power, 2015-05-13 16:34:02]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1138473003/1

[commit-bot: I haz the power, 2015-05-13 16:36:46]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-05-13 16:38:00]

Patchset 1 (id:??) landed as
https://crrev.com/4e9c2774d004a1fce0b1f572398e3b0c9e3337f7
Cr-Commit-Position: refs/heads/master@{#329654}

[Peter Kasting, 2015-05-13 22:51:29]

LGTM