ParseCandidate(): Refactor to fix memcheck false positive.
Also make supported protocols explicit in check.

Fix inconsistency where TLS_PROTOCOL_NAME was not exported.

BUG=webrtc:6885

Review-Url: https://codereview.webrtc.org/2570803003
Cr-Original-Commit-Position: refs/heads/master@{#15577}
Cr-Mirrored-From: https://chromium.googlesource.com/external/webrtc
Cr-Mirrored-Commit: b68cc75f1959218970df168b4c1b6e724692ac39
2 files changed