Preparation CL to remove RTPTypeHeader. Bug: none Change-Id: I695acf20082b94744a2f6c7692f1b2128932cd79 Reviewed-on: https://webrtc-review.googlesource.com/86132 Reviewed-by: Stefan Holmer <stefan@webrtc.org> Reviewed-by: Danil Chapovalov <danilchap@webrtc.org> Commit-Queue: Philip Eliasson <philipel@webrtc.org> Cr-Commit-Position: refs/heads/master@{#23835}