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

media/cast/transport/rtp_sender/rtp_sender.cc

 // 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.
 
 #include "media/cast/transport/rtp_sender/rtp_sender.h"
 
 #include "base/logging.h"
 #include "base/rand_util.h"
 #include "media/cast/transport/cast_transport_defines.h"
 #include "media/cast/transport/pacing/paced_sender.h"
@@ skipping 57 matching lines @@
   return true;
 }
 
 void RtpSender::SendFrame(const EncodedFrame& frame) {
   DCHECK(packetizer_);
   packetizer_->SendFrameAsPackets(frame);
 }
 
 void RtpSender::ResendPackets(
     const MissingFramesAndPacketsMap& missing_frames_and_packets,
-    bool cancel_rtx_if_not_in_list) {
+    bool cancel_rtx_if_not_in_list,
+    base::TimeDelta rtt) {
   DCHECK(storage_);
   // Iterate over all frames in the list.
   for (MissingFramesAndPacketsMap::const_iterator it =
            missing_frames_and_packets.begin();
        it != missing_frames_and_packets.end();
        ++it) {
     SendPacketVector packets_to_resend;
     uint8 frame_id = it->first;
     // Set of packets that the receiver wants us to re-send.
     // If empty, we need to re-send all packets for this frame.
@@ skipping 33 matching lines @@
         VLOG(3) << "Resend " << static_cast<int>(frame_id) << ":"
                 << packet_id;
         // Set a unique incremental sequence number for every packet.
         PacketRef packet_copy = FastCopyPacket(it->second);
         UpdateSequenceNumber(&packet_copy->data);
         packets_to_resend.push_back(std::make_pair(packet_key, packet_copy));
       } else if (cancel_rtx_if_not_in_list) {
         transport_->CancelSendingPacket(it->first);
       }
     }
-    transport_->ResendPackets(packets_to_resend);
+    transport_->ResendPackets(packets_to_resend, rtt);
   }
 }
 
 void RtpSender::UpdateSequenceNumber(Packet* packet) {
   uint16 new_sequence_number = packetizer_->NextSequenceNumber();
   int index = 2;
   (*packet)[index] = (static_cast<uint8>(new_sequence_number));
   (*packet)[index + 1] = (static_cast<uint8>(new_sequence_number >> 8));
 }
 
 }  // namespace transport
 }  //  namespace cast
 }  // namespace media