as an alternative to NextPacket function
to allow cleaner iterating over stacked rtcp packets.
Bug: webrtc:5565
Change-Id: I261afe2684e5fcb5fa3e7bcce272fbefeebd0b66
Reviewed-on: https://webrtc-review.googlesource.com/21360
Reviewed-by: Niels Moller <nisse@webrtc.org>
Commit-Queue: Danil Chapovalov <danilchap@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#20615}