Move ownership of SigninNotificationController upstream.

Move ownership of SigninNotificationController upstream.

Previously owned by GSM downstream. Note that there will be
two SigninNotificationControllers in existence between this
landing and the downstream patch landing, but the only call
its listener makes (cancelNotification) appears to be
idempotent so it shouldn't matter.

BUG=428882
Committed: https://crrev.com/5ef8fe826e1347681923b959b596751028b75d2a
Cr-Commit-Position: refs/heads/master@{#319091}

[maxbogue, 2015-02-26 22:49:46]

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

[maxbogue, 2015-02-26 22:49:46]

PTAL, thanks!

[maxbogue, 2015-03-02 18:18:57]

Bump; this is a small change and should not require much time to review.

[nyquist, 2015-03-04 09:16:04]

lgtm

[maxbogue, 2015-03-04 18:20:48]

The CQ bit was checked by maxbogue@chromium.org

[commit-bot: I haz the power, 2015-03-04 18:22:29]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/952083002/1

[commit-bot: I haz the power, 2015-03-04 18:53:51]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-03-04 18:55:15]

Patchset 1 (id:??) landed as
https://crrev.com/5ef8fe826e1347681923b959b596751028b75d2a
Cr-Commit-Position: refs/heads/master@{#319091}