Register sample rate of Audio RED in RTPPayloadRegistry.

Sample rate of RED payload type was not registered. And therefore VoE can fail when it receives RED packets. This is a fix to this problem.

BUG=3619
R=henrik.lundin@webrtc.org, stefan@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/43919004

Cr-Commit-Position: refs/heads/master@{#8859}
2 files changed