am 1580fa99: am ca6e4e3c: Merge "Implement onPlayDtmfTone and onStopDtmfTone in Conferences" into lmp-dev

* commit '1580fa99bd0ae981ee984ce3c51cc640e50805d2':
  Implement onPlayDtmfTone and onStopDtmfTone in Conferences