Handle the PROTO_TSL when getting the protocol priority.

This bug breaks the internal project.

TBR=deadbeef@webrtc.org, pthacher@webrtc.org
BUG=webrtc:7889

Review-Url: https://codereview.webrtc.org/2959993002
Cr-Original-Commit-Position: refs/heads/master@{#18792}
Cr-Mirrored-From: https://chromium.googlesource.com/external/webrtc
Cr-Mirrored-Commit: 696f8ca2fa29b950518525b2f20b4e9c6052ddfd
1 file changed