Reland of [Extensions] Migrate ServiceWorker off behavior feature system

Reland of [Extensions] Migrate ServiceWorker off behavior feature system (patchset #1 id:1 of https://codereview.chromium.org/1412683007/ )

Reason for revert:
Talked to Anthony offline and we agreed the error was probably not my CL.

Original issue's description:
> Revert of [Extensions] Migrate ServiceWorker off behavior feature system (patchset #1 id:1 of https://codereview.chromium.org/1417563005/ )
>
> Reason for revert:
> Reverting because this CL appears to be causing failures on this bot: https://build.chromium.org/p/chromium.win/builders/Win%20x64%20Builder%20%28dbg%29/builds/14499 .
>
> Original issue's description:
> > [Extensions] Migrate ServiceWorker off behavior feature system
> >
> > The FeatureSystem is failing to retrieve the behavior feature for service
> > workers, but the only reason this seems to be the case is because of
> > potential corruption in the JSON files (or the JSON parser otherwise choking).
> > For now, to reduce the crash rates, just migrate the service worker restriction
> > off the behavior feature system.
> >
> > BUG=461915
> >
> > Committed: https://crrev.com/2507a2fcd25244dadb7dfcc316426bee7b1df275
> > Cr-Commit-Position: refs/heads/master@{#356123}
>
> TBR=rockot@chromium.org,rdevlin.cronin@chromium.org
> NOPRESUBMIT=true
> NOTREECHECKS=true
> NOTRY=true
> BUG=461915
>
> Committed: https://crrev.com/5708524cd0517ad825093d8cb4e9171ca99b3f42
> Cr-Commit-Position: refs/heads/master@{#356137}

TBR=rockot@chromium.org,anthonyvd@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=461915
Committed: https://crrev.com/a6a8e75c2ae8ad637e69130d831154f1ad9f454d
Cr-Commit-Position: refs/heads/master@{#356152}

[Devlin, 2015-10-26 22:24:39]

Created Reland of [Extensions] Migrate ServiceWorker off behavior feature system

[commit-bot: I haz the power, 2015-10-26 22:26:08]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1406083004/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1406083004/1

[commit-bot: I haz the power, 2015-10-26 22:27:48]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-10-26 22:28:53]

Patchset 1 (id:??) landed as
https://crrev.com/a6a8e75c2ae8ad637e69130d831154f1ad9f454d
Cr-Commit-Position: refs/heads/master@{#356152}