I'll be doing some changes to code it tests (rtp_receiver_audio,
specifically) and want to make sure there are tests in place before I
touch anything.
Fixed test_api_audio not properly checking payload data. Required a
fix to LoopBackTransport in test_api to as to act like the regular
audio and video parts of WebRTC and separate payload from header data.
Also added a test for CNG and cleaned up constants.
BUG=webrtc:5805
Review-Url: https://codereview.webrtc.org/2378403004
Cr-Commit-Position: refs/heads/master@{#14529}
b2d1e0d1da