Refactoring PayloadRouter.

- Move PayloadRouter to RtpTransportControllerInterface.
- Move RetransmissionLimiter inside RtpTransportControllerSend from
  VideoSendStreamImpl.
- Move video RTP specifics into PayloadRouter, in particular ownership
  of the RTP modules.
- PayloadRouter now contains all video specific RTP code, and will be
  renamed in a follow-up to VideoRtpSender.
- Introduce VideoRtpSenderInterface.

Bug: webrtc:9517
Change-Id: I1c7b293fa6f9c320286c80533b3c584498034a38
Reviewed-on: https://webrtc-review.googlesource.com/88240
Commit-Queue: Stefan Holmer <stefan@webrtc.org>
Reviewed-by: Sebastian Jansson <srte@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#24009}
diff --git a/modules/video_coding/session_info.cc b/modules/video_coding/session_info.cc
index 1b6f732..834684e 100644
--- a/modules/video_coding/session_info.cc
+++ b/modules/video_coding/session_info.cc
@@ -33,6 +33,8 @@
       first_packet_seq_num_(-1),
       last_packet_seq_num_(-1) {}
 
+VCMSessionInfo::~VCMSessionInfo() {}
+
 void VCMSessionInfo::UpdateDataPointers(const uint8_t* old_base_ptr,
                                         const uint8_t* new_base_ptr) {
   for (PacketIterator it = packets_.begin(); it != packets_.end(); ++it)