Revert of [Background Sync] Allow sync manager access from uncontrolled clients

Revert of [Background Sync] Allow sync manager access from uncontrolled clients (patchset #2 id:20001 of https://codereview.chromium.org/1316743002/ )

Reason for revert:
This is breaking background_sync LayoutTests:
http://build.chromium.org/p/chromium.webkit/builders/WebKit%20Linux/builds/53395

I guess part 3 would have fixed that but it doesn't seem to be ready to land.

Original issue's description:
> [Background Sync] Allow sync manager access from uncontrolled clients
>
> This patch removes the requirement for the caller of a BackgroundSync
> manager method to be either a service worker or a controlled client.
> Now, uncontrolled clients are also able to access the manager, and Blink
> informs the browser whether a registration request came from a Service
> Worker or not. (Service Workers are still required to have at least one
> active window client in order to register sync events; this is enforced
> in the browser).
>
> This is part 2 of a three-part blink-chromium-blink dance.
> Part 1: https://codereview.chromium.org/1309393003
> Part 2: https://codereview.chromium.org/1316743002 (this patch)
> Part 3: https://codereview.chromium.org/1314453003
>
> BUG=518884
>
> Committed: https://crrev.com/d7c429ff6d306e720d6b0e7b64be25c8efad82d8
> Cr-Commit-Position: refs/heads/master@{#346459}

TBR=jkarlin@chromium.org,tsepez@chromium.org,iclelland@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=518884
Committed: https://crrev.com/9a31c59a3d7e2b90a8bf97b3432fd1a2fdc1820e
Cr-Commit-Position: refs/heads/master@{#346613}

[mlamouri (slow - plz ping), 2015-09-01 10:12:00]

Created Revert of [Background Sync] Allow sync manager access from uncontrolled
clients

[commit-bot: I haz the power, 2015-09-01 10:12:26]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1317813003/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1317813003/1

[commit-bot: I haz the power, 2015-09-01 10:13:05]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-09-01 10:13:35]

Patchset 1 (id:??) landed as
https://crrev.com/9a31c59a3d7e2b90a8bf97b3432fd1a2fdc1820e
Cr-Commit-Position: refs/heads/master@{#346613}