Let WebRtcVideoChannel2::WebRtcVideoSendStream::InputFrame carry the input frame's timestamp to output frame.

Essentially we are carrying over the capture timestamp to the encoded frame sent out, so the frame lengths will contain no noise.

Review URL: https://codereview.webrtc.org/1225153002

Cr-Commit-Position: refs/heads/master@{#9597}
6 files changed