There are some internal projects that need to be updated before we remove StartRtcEventLog and StopRtcEventLog. In this CL we take away the pure-virtuality status of the functions. After landing this, we can fix the internal projects, then land https://webrtc-review.googlesource.com/c/src/+/6782. TBR=stefan@webrtc.org Bug: webrtc:8111 Change-Id: Ibe495a7e7d6bf8120b1a26f056bd1443031733bf Reviewed-on: https://webrtc-review.googlesource.com/6980 Commit-Queue: Elad Alon <eladalon@webrtc.org> Reviewed-by: Karl Wiberg <kwiberg@webrtc.org> Reviewed-by: Ivo Creusen <ivoc@webrtc.org> Reviewed-by: Björn Terelius <terelius@webrtc.org> Cr-Commit-Position: refs/heads/master@{#20178}