The declarations of DeregisterExternalDecoder and RegisterExternalDecoder were accidentally copied into encoder_database.h in previous cl https://webrtc-review.googlesource.com/55562. Bug: webrtc:8830 Change-Id: I5982d8f3e02b1a9d0305ec2b867876662bbc9ef3 Reviewed-on: https://webrtc-review.googlesource.com/56043 Reviewed-by: Rasmus Brandt <brandtr@webrtc.org> Commit-Queue: Niels Moller <nisse@webrtc.org> Cr-Commit-Position: refs/heads/master@{#22149}