to avoid expensive move of the Packet and prepare PacketBuffer to return list of packets as a frame. Bug: None Change-Id: I19f0452c52238228bbe28284ebb197491eb2bf4e Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/167063 Reviewed-by: Philip Eliasson <philipel@webrtc.org> Reviewed-by: Erik Språng <sprang@webrtc.org> Commit-Queue: Danil Chapovalov <danilchap@webrtc.org> Cr-Commit-Position: refs/heads/master@{#30404}