Delete VideoReceiveStream::Config::pre_render_callback.

Also delete the class I420FrameCallback.

BUG=webrtc:7124

Review-Url: https://codereview.webrtc.org/2678343002
Cr-Original-Commit-Position: refs/heads/master@{#16478}
Cr-Mirrored-From: https://chromium.googlesource.com/external/webrtc
Cr-Mirrored-Commit: 76bc8e858ff288449163c97aa66928f2eecdfd28
7 files changed