Remove cricket::VideoProcessor and AddVideoProcessor() functionality

This functionality is not used internally in WebRTC. Also, it's not safe, because the frame is supposed to be read-only, and it will likely not work for texture frames.

R=pthatcher@webrtc.org

Review URL: https://codereview.webrtc.org/1296113002 .

Cr-Commit-Position: refs/heads/master@{#9753}
14 files changed