ReportBlock is the the real receiver report. Triggering rtt update on ReportBlock support clients that send receiver report blocks attached to SenderReport rather than ReceiverReport. Bug: webrtc:7996 Change-Id: Ie826fa09fd1bf0e5256e995649f66811b5192761 Reviewed-on: https://webrtc-review.googlesource.com/4040 Reviewed-by: Åsa Persson <asapersson@webrtc.org> Commit-Queue: Danil Chapovalov <danilchap@webrtc.org> Cr-Commit-Position: refs/heads/master@{#20014}