Hook in DTMF Transport.

Add the DtmfTransport to the Communicator created in TelephonyConnection.

Test: Added unit tests for DTMF transport.
Test: Manual test to verify protocol is attempted when call goes active.
Bug: 163085177Bug:
Change-Id: Id967b8f6aa71e8ea362772be543207325782e8c4
1 file changed