Move Ownership of RtpModules to VideoSendStream from VieChannel and remove use of vie_channel and vie_receiver from video_send_stream.

The purpose of this refactoring is a first step of separating the encoder parts from the RTP transport.

BUG=webrtc:5687
R=mflodman@webrtc.org, pbos@webrtc.org, stefan@webrtc.org

Review URL: https://codereview.webrtc.org/1864313003 .

Cr-Original-Commit-Position: refs/heads/master@{#12377}
Cr-Mirrored-From: https://chromium.googlesource.com/external/webrtc
Cr-Mirrored-Commit: 83d09106943b3b70d9aaa92bc674fae473443f89
17 files changed