Revert of Start moving ownership of SyncNotificationController to SyncController...

Revert of Start moving ownership of SyncNotificationController to SyncController. (patchset #3 id:40001 of https://codereview.chromium.org/889723002/)

Reason for revert:
Broke downstream builds

Original issue's description:
> Start moving ownership of SyncNotificationController to SyncController.
>
> GoogleServicesNotificationController is modified to work
> the way most other singleton classes work, so that it is
> not necessary to pass into the SyncNotificationController
> constructor (and thus, into SyncController in the future).
>
> SyncController gets a temporary setter method so that SNC
> can be constructed downstream and passed in until all its
> dependencies are upstream.
>
> BUG=428882
>
> Committed: https://crrev.com/deaa0fe6ca3e0428a85fc22b019819437d84120b
> Cr-Commit-Position: refs/heads/master@{#314515}

TBR=nyquist@chromium.org,maxbogue@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=428882

Review URL: https://codereview.chromium.org/895373002

Cr-Commit-Position: refs/heads/master@{#314537}