- Replace few sigslot usages in jsep_transport_controller. - There is still one sigslot usages in this file so keeping the inheritance and that is the reason for not having a binary size gain in this CL. - Remaining sigslot will be removed in a separate CL. Bug: webrtc:11943 Change-Id: Idb8fa1090b037c48eeb62f54cffd3c485cebfcda Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/190146 Reviewed-by: Andrey Logvin <landrey@webrtc.org> Reviewed-by: Mirko Bonadei <mbonadei@webrtc.org> Reviewed-by: Harald Alvestrand <hta@webrtc.org> Reviewed-by: Lahiru Ginnaliya Gamathige <glahiru@webrtc.org> Commit-Queue: Lahiru Ginnaliya Gamathige <glahiru@webrtc.org> Cr-Commit-Position: refs/heads/master@{#33034}