Re-land "Convert native handles to buffers before encoding."

This reverts commit a67675506c9057bd9ffd4d76aae8b743343d434d.

BUG=webrtc:4081
TBR=magjed@webrtc.org

Review URL: https://codereview.webrtc.org/1158273010

Cr-Commit-Position: refs/heads/master@{#9381}
19 files changed