Needed to be able to add an SdpVideoFormat member to
VideoEncoderConfig or other move-only classes.
Bug: webrtc:8830
Change-Id: Ie15dbfec616b059e1492d2c17ebd210f0edbe00f
Reviewed-on: https://webrtc-review.googlesource.com/64983
Reviewed-by: Karl Wiberg <kwiberg@webrtc.org>
Commit-Queue: Niels Moller <nisse@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#22642}