[rtp_rtcp] fixed lint errors in rtp_rtcp module that are not fixed in other CLs

webrtc/modules/rtp_rtcp/source/rtp_packet_history.h

 /*
  *  Copyright (c) 2012 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.
  *
  *  Class for storing RTP packets.
@@ skipping 11 matching lines @@
 
 namespace webrtc {
 
 class Clock;
 class CriticalSectionWrapper;
 
 static const size_t kMaxHistoryCapacity = 9600;
 
 class RTPPacketHistory {
  public:
-  RTPPacketHistory(Clock* clock);
+  explicit RTPPacketHistory(Clock* clock);
   ~RTPPacketHistory();
 
   void SetStorePacketsStatus(bool enable, uint16_t number_to_store);
 
   bool StorePackets() const;
 
   // Stores RTP packet.
   int32_t PutRTPPacket(const uint8_t* packet,
                        size_t packet_length,
                        int64_t capture_time_ms,
@@ skipping 52 matching lines @@
     StorageType storage_type = kDontRetransmit;
     bool has_been_retransmitted = false;
 
     uint8_t data[IP_PACKET_SIZE];
     size_t length = 0;
   };
   std::vector<StoredPacket> stored_packets_ GUARDED_BY(critsect_);
 };
 }  // namespace webrtc
 #endif  // WEBRTC_MODULES_RTP_RTCP_SOURCE_RTP_PACKET_HISTORY_H_