Remove rtcp_utility as mostly unused.

webrtc/modules/rtp_rtcp/source/rtcp_nack_stats.h

+/*
+*  Copyright (c) 2017 The WebRTC project authors. All Rights Reserved.
+*
+*  Use of this source code is governed by a BSD-style license
+*  that can be found in the LICENSE file in the root of the source
+*  tree. An additional intellectual property rights grant can be found
+*  in the file PATENTS.  All contributing project authors may
+*  be found in the AUTHORS file in the root of the source tree.
+*/
+
+#ifndef WEBRTC_MODULES_RTP_RTCP_SOURCE_RTCP_NACK_STATS_H_
+#define WEBRTC_MODULES_RTP_RTCP_SOURCE_RTCP_NACK_STATS_H_
+
+#include <stdint.h>
+
+namespace webrtc {
+
+class RtcpNackStats {
+ public:
+  RtcpNackStats();
+
+  // Updates stats with requested sequence number.
+  // This function should be called for each NACK request to calculate the
+  // number of unique NACKed RTP packets.
+  void ReportRequest(uint16_t sequence_number);
+
+  // Gets the number of NACKed RTP packets.
+  uint32_t requests() const { return requests_; }
+
+  // Gets the number of unique NACKed RTP packets.
+  uint32_t unique_requests() const { return unique_requests_; }
+
+ private:
+  uint16_t max_sequence_number_;
+  uint32_t requests_;
+  uint32_t unique_requests_;
+};
+
+}  // namespace webrtc
+#endif  // WEBRTC_MODULES_RTP_RTCP_SOURCE_RTCP_NACK_STATS_H_