Start moving ownership of SyncNotificationController to SyncController, take 2.

Start moving ownership of SyncNotificationController to SyncController, take 2.

Original: http://crrev.com/889723002
Reverted: http://crrev.com/895373002

This version restores a missing @VisibleForTests annotation
to GoogleServicesNotificationController.getInstance(). Its
removal caused the method to be pruned on build, breaking
downstream tests that depended on it.

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/d6674cc202f506329d414a3aeb17dccb26f30bdb
Cr-Commit-Position: refs/heads/master@{#315367}

[maxbogue, 2015-02-04 18:56:15]

maxbogue@chromium.org changed reviewers:
+ nyquist@chromium.org

[maxbogue, 2015-02-04 18:56:16]

Let's try this again.

[nyquist, 2015-02-05 23:23:46]

lgtm

[maxbogue, 2015-02-09 19:37:24]

The CQ bit was checked by maxbogue@chromium.org

[commit-bot: I haz the power, 2015-02-09 19:38:50]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/895283003/1

[commit-bot: I haz the power, 2015-02-09 20:01:47]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-02-09 20:02:36]

Patchset 1 (id:??) landed as
https://crrev.com/d6674cc202f506329d414a3aeb17dccb26f30bdb
Cr-Commit-Position: refs/heads/master@{#315367}