257ed437f0
Optional fields are those which only occur sometimes. For example, the sequence number field in an RTP packet always occurs, but fields in optional RTP extensions only occur sometimes. Bug: webrtc:8111 Change-Id: Iff2c35b73530c0a1db68e547b4caf34434aa4ace Reviewed-on: https://webrtc-review.googlesource.com/c/103362 Commit-Queue: Elad Alon <eladalon@webrtc.org> Reviewed-by: Björn Terelius <terelius@webrtc.org> Cr-Commit-Position: refs/heads/master@{#25336}