Merge changes I71a37663,Ib2010b38

* changes:
  Improve testing of registerSystemDefaultNetworkCallback.
  Remove buggy ConnectivityManagerTest#ensureWifiConnected.
tree: 146e72a527fcad428f1e3a2845ae9d6de8153936
  1. tests/
  2. Tethering/
  3. .gitignore
  4. OWNERS
  5. PREUPLOAD.cfg
  6. TEST_MAPPING