This is the first step of migrating SupportsProtocol() to
absl::string_view. The std::string version will be removed once all
downstream users have migrated and have implemented the
absl::string_view version.
Bug: webrtc:13579
Change-Id: Ib609b9bab0c2e525553daddb1e365050bbe1c1f5
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/265806
Reviewed-by: Harald Alvestrand <hta@webrtc.org>
Commit-Queue: Ali Tofigh <alito@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#37211}