Per the latest WebRTC stats spec
(https://w3c.github.io/webrtc-stats/#dom-rtcicecandidatestats)
the address field of a peer-reflexive remote candidate should be concealed
until the same address is learnt via addIceCandidate.
This CL also refactors the sanitization-related code paths.
Bug: chromium:968161
Change-Id: I74c5da78232b2f604689867bda2937b8af827c4f
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/149381
Reviewed-by: Steve Anton <steveanton@webrtc.org>
Commit-Queue: Qingsi Wang <qingsi@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#28909}