Merge changes I638ed5cd,I29f15571,I21a22ed1

* changes:
  Expose registerDefaultNetworkCallbackAsUid.
  Support calling registerDefaultNetworkCallback for another UID.
  Store the effective UID in NetworkRequestInfo.
tree: 0b6fd19f052b0297203868f32e22facb6180ba08
  1. core/
  2. framework/
  3. service/
  4. services/
  5. tests/
  6. OWNERS
  7. TEST_MAPPING