Change PacketKey to be unique for each frame packet by including

media/cast/net/rtp/rtp_sender.cc

Index: media/cast/net/rtp/rtp_sender.cc
diff --git a/media/cast/net/rtp/rtp_sender.cc b/media/cast/net/rtp/rtp_sender.cc
index f24f346baca622c2cdb46b787e94e32be3a7e508..bd822e88215420e9788217493c1c536deb4f62a7 100644
--- a/media/cast/net/rtp/rtp_sender.cc
+++ b/media/cast/net/rtp/rtp_sender.cc
@@ -77,7 +77,7 @@ void RtpSender::ResendPackets(
     for (SendPacketVector::const_iterator it = stored_packets->begin();
          it != stored_packets->end(); ++it) {
       const PacketKey& packet_key = it->first;
-      const uint16 packet_id = packet_key.second.second;
+      const uint16 packet_id = packet_key.packet_id;
 
       // Should we resend the packet?
       bool resend = resend_all;