Rename structures to match terminology in the spec
Bug: webrtc:10342
Change-Id: I1329abaca98ae7f82307451032d5ce1533e80772
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/143960
Reviewed-by: Philip Eliasson <philipel@webrtc.org>
Commit-Queue: Danil Chapovalov <danilchap@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#28402}