Moving the responsibility for calling callbacks from implementations of NetworkControllerInterface to SendSideCongestionController. This decreases the coupling and makes the callbacks more explicit. Bug: webrtc:8415 Change-Id: Ie75effbde01533106080bb6c40308b0c20064c45 Reviewed-on: https://webrtc-review.googlesource.com/66882 Commit-Queue: Sebastian Jansson <srte@webrtc.org> Reviewed-by: Niels Moller <nisse@webrtc.org> Cr-Commit-Position: refs/heads/master@{#22793}