This method will be called when PacedSender is using the new code path
that directly owns the packets to be sent.
It can be seen as combining a few features of the old code path:
* It checks if this is the correct RTP module and then sends, without
the need for PacketRouter to poll multiple methods for SSRC etc first.
* It partly corresponds to TimeToSendPacket(), but RTX encapsulation
now happens pre-pacer and FEC does not need to have a packet history,
so most of that method is not used.
* It implements most of PrepareAndSendPacket(), such as updating header
extensions, reporting stats and of course forwards to Transport. It
now also handles the history a bit differently, since media packets
will only be stored for potential retransmission post-pacer.
Bug: webrtc:10633
Change-Id: Ie97952eeef6e56e462e115d67f7c7929f36c1817
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/142165
Commit-Queue: Erik Språng <sprang@webrtc.org>
Reviewed-by: Ilya Nikolaevskiy <ilnik@webrtc.org>
Reviewed-by: Danil Chapovalov <danilchap@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#28298}