rtcp::Nack packet moved into own file and got Parse function

webrtc/modules/rtp_rtcp/source/rtcp_packet.cc

Index: webrtc/modules/rtp_rtcp/source/rtcp_packet.cc
diff --git a/webrtc/modules/rtp_rtcp/source/rtcp_packet.cc b/webrtc/modules/rtp_rtcp/source/rtcp_packet.cc
index be03d9b41a7606c66f8c45bc52d7a3d606273b12..fe251e01319a8ec932b382a3e40c0cd072e934b2 100644
--- a/webrtc/modules/rtp_rtcp/source/rtcp_packet.cc
+++ b/webrtc/modules/rtp_rtcp/source/rtcp_packet.cc
@@ -279,31 +279,6 @@ void CreateSli(const RTCPPacketPSFBSLI& sli,
   AssignUWord8(buffer, pos, (sli_item.NumberOfMB << 6) + sli_item.PictureId);
 }
 
-// Generic NACK (RFC 4585).
-//
-// FCI:
-//
-//    0                   1                   2                   3
-//    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
-//   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-//   |            PID                |             BLP               |
-//   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-
-void CreateNack(const RTCPPacketRTPFBNACK& nack,
-                const std::vector<RTCPPacketRTPFBNACKItem>& nack_fields,
-                size_t start_index,
-                size_t end_index,
-                uint8_t* buffer,
-                size_t* pos) {
-  AssignUWord32(buffer, pos, nack.SenderSSRC);
-  AssignUWord32(buffer, pos, nack.MediaSSRC);
-  for (size_t i = start_index; i < end_index; ++i) {
-    const RTCPPacketRTPFBNACKItem& nack_item = nack_fields[i];
-    AssignUWord16(buffer, pos, nack_item.PacketID);
-    AssignUWord16(buffer, pos, nack_item.BitMask);
-  }
-}
-
 // Reference picture selection indication (RPSI) (RFC 4585).
 //
 // FCI:
@@ -852,65 +827,6 @@ bool Sli::Create(uint8_t* packet,
   return true;
 }
 
-bool Nack::Create(uint8_t* packet,
-                  size_t* index,
-                  size_t max_length,
-                  RtcpPacket::PacketReadyCallback* callback) const {
-  assert(!nack_fields_.empty());
-  // If nack list can't fit in packet, try to fragment.
-  size_t nack_index = 0;
-  do {
-    size_t bytes_left_in_buffer = max_length - *index;
-    if (bytes_left_in_buffer < kCommonFbFmtLength + 4) {
-      if (!OnBufferFull(packet, index, callback))
-        return false;
-      continue;
-    }
-    int64_t num_nack_fields =
-        std::min((bytes_left_in_buffer - kCommonFbFmtLength) / 4,
-                 nack_fields_.size() - nack_index);
-
-    const uint8_t kFmt = 1;
-    size_t size_bytes = (num_nack_fields * 4) + kCommonFbFmtLength;
-    size_t header_length = ((size_bytes + 3) / 4) - 1;  // As 32bit words - 1
-    CreateHeader(kFmt, PT_RTPFB, header_length, packet, index);
-    CreateNack(nack_, nack_fields_, nack_index, nack_index + num_nack_fields,
-               packet, index);
-
-    nack_index += num_nack_fields;
-  } while (nack_index < nack_fields_.size());
-
-  return true;
-}
-
-size_t Nack::BlockLength() const {
-  return (nack_fields_.size() * 4) + kCommonFbFmtLength;
-}
-
-void Nack::WithList(const uint16_t* nack_list, int length) {
-  assert(nack_list);
-  assert(nack_fields_.empty());
-  int i = 0;
-  while (i < length) {
-    uint16_t pid = nack_list[i++];
-    // Bitmask specifies losses in any of the 16 packets following the pid.
-    uint16_t bitmask = 0;
-    while (i < length) {
-      int shift = static_cast<uint16_t>(nack_list[i] - pid) - 1;
-      if (shift >= 0 && shift <= 15) {
-        bitmask |= (1 << shift);
-        ++i;
-      } else {
-        break;
-      }
-    }
-    RTCPUtility::RTCPPacketRTPFBNACKItem item;
-    item.PacketID = pid;
-    item.BitMask = bitmask;
-    nack_fields_.push_back(item);
-  }
-}
-
 bool Rpsi::Create(uint8_t* packet,
                   size_t* index,
                   size_t max_length,