Fix timing between bcast and net setup.

A legacy network type request would generate a bcast before the network
notification was sent - the legacy startUsingNetworkFeature API requires
the notification so it can bind your dns queries to the new network.
Fast-moving clients could try to use the network before it was ready.

bug:18792871
Change-Id: I24c46ef15c249c50bfc321f62756d1f66dc3a6a9