class to pass packet to RtcpPacketParser This helpers make tests setup cleaner and makes explicit expectation on number of packets passed to the transport. Bug: webrtc:8239 Change-Id: I2d5975be59327cee440e87dbd0701b93514c9726 Reviewed-on: https://webrtc-review.googlesource.com/22460 Commit-Queue: Danil Chapovalov <danilchap@webrtc.org> Reviewed-by: Niels Moller <nisse@webrtc.org> Cr-Commit-Position: refs/heads/master@{#20911}