Removes automatic setting of COMM mode in WebRTC.
It is now up to the application to ensure that it is in COMM mode before any audio streaming is started.

BUG=b/21571563
R=glaznev@webrtc.org

Review URL: https://codereview.webrtc.org/1165923002

Cr-Commit-Position: refs/heads/master@{#9383}
5 files changed