Merge changes I6a48d4db,I6741c41c,Ifec6bde5,Icd0717c5

* changes:
  Remove unused variables
  Return offloaded traffic when querying from TrafficStats API
  Add hardware tethering traffic in testTethering test
  Remove unused getTetherStats
tree: c598dea0ca08e5c0cd91f4411bba80b2e3ef0721
  1. core/
  2. services/
  3. tests/