Looking at bug 1414169, it appears that the intent is to display all candidates that the other end has given us (either via trickle, or via SDP).

Right now we are populating this list in two places:

https://searchfox.org/mozilla-central/rev/ebe492edacc75bb122a2b380e4cafcca3470864c/media/webrtc/signaling/src/peerconnection/PeerConnectionImpl.cpp#2666-2669

https://searchfox.org/mozilla-central/rev/ebe492edacc75bb122a2b380e4cafcca3470864c/media/webrtc/signaling/src/peerconnection/MediaTransportHandler.cpp#1124-1127

These two places give us very different lists, which when taken together do not actually give us what we intended. The first only gives us trickle candidates that come in while we're in stable; it does not give us trickle candidates that come in before that. This list is also not cleared when the transports change; old candidates can persist. The second only gives us the remote candidates that the ICE stack is currently using; disabled components aren't reflected, and nothing shows up if pairing has not happened yet. Also, peer reflexives are included in the second case.

We need to define what we want to display here a little more thoroughly.