This reverts commit 8efc914cf353cea138a453c45e970e589bec0834.
Reason for revert: Breaks downstream project.
Original change's description:
> Replace use of sigslot with CallbackList in data_channel_controller
>
> This is a straightforward replacement; simplifications due to the ability
> to inline functions in the lambdas are for a later CL.
>
> Bug: webrtc:11943
> Change-Id: I7274cedde507b954f1d8aa8bc560861102eeb264
> Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/250540
> Reviewed-by: Niels Moller <nisse@webrtc.org>
> Commit-Queue: Harald Alvestrand <hta@webrtc.org>
> Cr-Commit-Position: refs/heads/main@{#35936}
TBR=nisse@webrtc.org,hta@webrtc.org,webrtc-scoped@luci-project-accounts.iam.gserviceaccount.com
Change-Id: I8fd0f32ceec866bfd9a08cac1108b559bf03caac
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: webrtc:11943
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/251280
Owners-Override: Mirko Bonadei <mbonadei@webrtc.org>
Bot-Commit: rubber-stamper@appspot.gserviceaccount.com <rubber-stamper@appspot.gserviceaccount.com>
Commit-Queue: Mirko Bonadei <mbonadei@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#35941}
e0bc8d2f49