"PROTO_TCP + secure bit" was turned into "PROTO_TLS" by this CL: https://codereview.webrtc.org/2568833002 But a "DCHECK(proto == PROTO_TCP)" wasn't updated to take this into account. BUG=NONE TBR=pthatcher@webrtc.org Review-Url: https://codereview.webrtc.org/2859763003 Cr-Commit-Position: refs/heads/master@{#18000}