Move RtpPacketSender and merge it with RtpPacketPacer.

This interface is intended to only handle packet-sending parts of the
paced sender.

See https://webrtc-review.googlesource.com/c/src/+/145212 for context

Bug: webrtc:10809
Change-Id: I93f0b40e1865665c2d436db67021350a0ed0687b
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/145216
Commit-Queue: Erik Språng <sprang@webrtc.org>
Reviewed-by: Stefan Holmer <stefan@webrtc.org>
Reviewed-by: Sebastian Jansson <srte@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#28662}
diff --git a/audio/channel_send.cc b/audio/channel_send.cc
index 72eacb3..f00e0dcd 100644
--- a/audio/channel_send.cc
+++ b/audio/channel_send.cc
@@ -365,11 +365,11 @@
   TransportSequenceNumberAllocator* seq_num_allocator_ RTC_GUARDED_BY(&crit_);
 };
 
-class RtpPacketSenderProxy : public RtpPacketPacer {
+class RtpPacketSenderProxy : public RtpPacketSender {
  public:
   RtpPacketSenderProxy() : rtp_packet_pacer_(nullptr) {}
 
-  void SetPacketPacer(RtpPacketPacer* rtp_packet_pacer) {
+  void SetPacketPacer(RtpPacketSender* rtp_packet_pacer) {
     RTC_DCHECK(thread_checker_.IsCurrent());
     rtc::CritScope lock(&crit_);
     rtp_packet_pacer_ = rtp_packet_pacer;
@@ -394,14 +394,10 @@
     }
   }
 
-  void SetAccountForAudioPackets(bool account_for_audio) override {
-    RTC_NOTREACHED();
-  }
-
  private:
   rtc::ThreadChecker thread_checker_;
   rtc::CriticalSection crit_;
-  RtpPacketPacer* rtp_packet_pacer_ RTC_GUARDED_BY(&crit_);
+  RtpPacketSender* rtp_packet_pacer_ RTC_GUARDED_BY(&crit_);
 };
 
 class VoERtcpObserver : public RtcpBandwidthObserver {
@@ -1005,7 +1001,7 @@
     RtpTransportControllerSendInterface* transport,
     RtcpBandwidthObserver* bandwidth_observer) {
   RTC_DCHECK_RUN_ON(&worker_thread_checker_);
-  RtpPacketPacer* rtp_packet_pacer = transport->packet_sender();
+  RtpPacketSender* rtp_packet_pacer = transport->packet_sender();
   TransportFeedbackObserver* transport_feedback_observer =
       transport->transport_feedback_observer();
   PacketRouter* packet_router = transport->packet_router();