1. Test NetworkCallbacks as well as CONNECTIVITY_ACTION, since we are moving away from CONNECTIVITY_ACTION. 2. Use the Network objects we get back to test Network#getSocketFactory(). 3. Check that TCP connections are closed with ECONNABORTED when a network disconnects. Bug: 28251576 Change-Id: I41a438b82ef9251e52866332f3445f1bf876e04f