With visibility restricted to modules/video_coding/.
Also drop some unneeded dependencies on system_wrappers.
Bug: webrtc:3380
Change-Id: If3b64396953a026bede09c9fb5eb06cfc4c29f3a
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/130104
Reviewed-by: Rasmus Brandt <brandtr@webrtc.org>
Commit-Queue: Niels Moller <nisse@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#27344}