Revert of Revert of Supervised user SafeSites: Expose & use API key from src-internal

Revert of Revert of Supervised user SafeSites: Expose & use API key from src-internal (patchset #1 id:1 of https://codereview.chromium.org/753683004/)

Reason for revert:
Relanding because the original reason for reverting looks like a flake rather than an issue with the CL.

Original issue's description:
> Revert of Supervised user SafeSites: Expose & use API key from src-internal (patchset #5 id:80001 of https://codereview.chromium.org/690423003/)
>
> Reason for revert:
> Build breakage on Mac:
>
> https://build.chromium.org/p/chromium.mac/builders/Mac%20Builder/builds/14318/steps/steps/logs/stdio
>
> Original issue's description:
> > Supervised user SafeSites: Expose & use API key from src-internal
> >
> > Key was added to src-internal in https://chromereviews.googleplex.com/113767014/
> >
> > BUG=417722
> >
> > Committed: https://crrev.com/2ee5f146d57d07bbad3804715e06590b850711f9
> > Cr-Commit-Position: refs/heads/master@{#305412}
>
> TBR=rogerta@chromium.org,bauerb@chromium.org,treib@chromium.org
> NOTREECHECKS=true
> NOTRY=true
> BUG=417722
>
> Committed: https://crrev.com/13c88c66f60e6364478a411e8ccf0bfd689f0a96
> Cr-Commit-Position: refs/heads/master@{#305413}

TBR=rogerta@chromium.org,bauerb@chromium.org,tnagel@chromium.org
NOTRY=true
BUG=417722
Committed: https://crrev.com/e81fd0f30e02e007ba86c63c9a1ce5299150fc54
Cr-Commit-Position: refs/heads/master@{#305416}

[Marc Treib, 2014-11-24 12:33:57]

Created Revert of Revert of Supervised user SafeSites: Expose & use API key from
src-internal

[Marc Treib, 2014-11-24 12:34:47]

The CQ bit was checked by treib@chromium.org

[commit-bot: I haz the power, 2014-11-24 12:35:25]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/756593002/1

[commit-bot: I haz the power, 2014-11-24 12:35:55]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2014-11-24 12:36:39]

Patchset 1 (id:??) landed as
https://crrev.com/e81fd0f30e02e007ba86c63c9a1ce5299150fc54
Cr-Commit-Position: refs/heads/master@{#305416}