Revert "Convert native handles to buffers before encoding."

This reverts commit a831dc3a7d10a1fbaa258ee6b1ca6cfc7e91c5ca to unblock
rolling into Chromium.

BUG=4081
TBR=magjed@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/55549004

Cr-Commit-Position: refs/heads/master@{#9354}
19 files changed