Cast: Avoid retransmit if we sent the same packet recently (less than RTT)

media/cast/transport/cast_transport_sender.h

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // This is the main interface for the cast transport sender.  It accepts encoded
 // frames (both audio and video), encrypts their encoded data, packetizes them
 // and feeds them into a transport (e.g., UDP).
 
 // Construction of the Cast Sender and the Cast Transport Sender should be done
 // in the following order:
@@ skipping 78 matching lines @@
                                      uint32 rtp_timestamp,
                                      const RtcpDlrrReportBlock& dlrr,
                                      uint32 sending_ssrc,
                                      const std::string& c_name) = 0;
 
   // Retransmission request.
   // |missing_packets| includes the list of frames and packets in each
   // frame to be re-transmitted.
   // If |cancel_rtx_if_not_in_list| is used as an optimization to cancel
   // pending re-transmission requests of packets not listed in
-  // |missing_packets|.
+  // |missing_packets|. If the requested packet(s) were sent recently
+  // (how long is specified by |dedupe_window|) then this re-transmit
+  // will be ignored.
   virtual void ResendPackets(
       bool is_audio,
       const MissingFramesAndPacketsMap& missing_packets,
-      bool cancel_rtx_if_not_in_list) = 0;
+      bool cancel_rtx_if_not_in_list,
+      base::TimeDelta dedupe_window) = 0;
 };
 
 }  // namespace transport
 }  // namespace cast
 }  // namespace media
 
 #endif  // MEDIA_CAST_TRANSPORT_CAST_TRANSPORT_SENDER_H_