Add TransportFeedback adapter, adapting remote feedback to bwe estiamtor

webrtc/modules/rtp_rtcp/interface/rtp_rtcp_defines.h

Index: webrtc/modules/rtp_rtcp/interface/rtp_rtcp_defines.h
diff --git a/webrtc/modules/rtp_rtcp/interface/rtp_rtcp_defines.h b/webrtc/modules/rtp_rtcp/interface/rtp_rtcp_defines.h
index 7642285caf152967f8a57542a2ea9803c35b6d55..f5897f742df62ef75aaf043c65d0ad56617ed121 100644
--- a/webrtc/modules/rtp_rtcp/interface/rtp_rtcp_defines.h
+++ b/webrtc/modules/rtp_rtcp/interface/rtp_rtcp_defines.h
@@ -24,6 +24,9 @@
 #define TIMEOUT_SEI_MESSAGES_MS 30000   // in milliseconds
 
 namespace webrtc {
+namespace rtcp {
+class TransportFeedback;
+}
 
 const int kVideoPayloadTypeFrequency = 90000;
 
@@ -293,15 +296,20 @@ class RtcpBandwidthObserver {
   virtual ~RtcpBandwidthObserver() {}
 };
 
-class SendTimeObserver {
+class TransportFeedbackObserver {
  public:
-  SendTimeObserver() {}
-  virtual ~SendTimeObserver() {}
+  TransportFeedbackObserver() {}
+  virtual ~TransportFeedbackObserver() {}
 
   // Transport-wide sequence number and timestamp (system time in milliseconds),
-  // of when the packet was put on the wire.
+  // of when the packet was put on the wire, size of packet in bytes, and
+  // whether the packet was sent through the paced sender or not.
   virtual void OnPacketSent(uint16_t transport_sequence_number,
-                            int64_t send_time) = 0;
+                            int64_t send_time,
+                            size_t size,
+                            bool was_paced) = 0;
+
+  virtual void OnTransportFeedback(const rtcp::TransportFeedback& feedback) = 0;
 };
 
 class RtcpRttStats {