- Removes the lock that was used to protect the audio transport object.
It is now protected "by design" instead.
- Removes rec/play_bytes_per_sample_ since we only support 16-bit samples.
BUG=webrtc:6560
R=kwiberg@webrtc.org
Review URL: https://codereview.webrtc.org/2466613002 .
Cr-Commit-Position: refs/heads/master@{#14950}