Reset NACK/ACK list when parsing a new RTCP packet.

media/cast/net/rtcp/rtcp_utility.cc

 // Copyright 2014 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/net/rtcp/rtcp_utility.h"
 
 #include <stdint.h>
 
 #include <cmath>
 
@@ skipping 304 matching lines @@
   uint8_t last_frame_id;
   uint8_t number_of_lost_fields;
   if (!reader->ReadU8(&last_frame_id) ||
       !reader->ReadU8(&number_of_lost_fields) ||
       !reader->ReadU16(&cast_message_.target_delay_ms))
     return false;
 
   // Please note, this frame_id is still only 8-bit!
   cast_message_.ack_frame_id = last_frame_id;
 
+  cast_message_.missing_frames_and_packets.clear();
+  cast_message_.received_later_frames.clear();
   for (size_t i = 0; i < number_of_lost_fields; i++) {
     uint8_t frame_id;
     uint16_t packet_id;
     uint8_t bitmask;
     if (!reader->ReadU8(&frame_id) ||
         !reader->ReadU16(&packet_id) ||
         !reader->ReadU8(&bitmask))
       return false;
     cast_message_.missing_frames_and_packets[frame_id].insert(packet_id);
     if (packet_id != kRtcpCastAllPacketsLost) {
@@ skipping 202 matching lines @@
   uint32_t ssrc_of_sender;
   base::BigEndianReader big_endian_reader(
       reinterpret_cast<const char*>(rtcp_buffer), length);
   big_endian_reader.Skip(4);  // Skip header.
   big_endian_reader.ReadU32(&ssrc_of_sender);
   return ssrc_of_sender;
 }
 
 }  // namespace cast
 }  // namespace media