Don't let NetworkMonitor state stop user-initiated transitions.

GCM can call reportInetCondition() at any time which can cause
the NetworkMonitor to transition states to reevaluate at any time.
Previously we were only listening for users clicking the sign-in
notificaiton or completing sign-in when in the appropriate state.
With this change NetworkMonitor's state does not stop us from
listening for the user's actions.

bug:17917929
Change-Id: Ic1da31d90f7090e5fc111874cb7c37d505aaf590