This ensures that only the compilation units that actually need ChannelManager details can see it. Bug: webrtc:13931 Change-Id: Iddd37580c0ceceba5b7095e84b981e6a525b2800 Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/261200 Commit-Queue: Harald Alvestrand <hta@webrtc.org> Reviewed-by: Henrik Boström <hbos@webrtc.org> Cr-Commit-Position: refs/heads/main@{#36762}