Media*Channel objects used to subclass webrtc::Transport. This was not an optimal design. This CL makes the transport a member variable of MediaChannelUtil. Bug: None Change-Id: I85d33cc1b32b931e563b7bb2d277f1c512600831 Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/309800 Commit-Queue: Harald Alvestrand <hta@webrtc.org> Reviewed-by: Florent Castelli <orphis@webrtc.org> Cr-Commit-Position: refs/heads/main@{#40328}