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

webrtc/modules/rtp_rtcp/source/fec_receiver_impl.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.
  */
 
 #ifndef WEBRTC_MODULES_RTP_RTCP_SOURCE_FEC_RECEIVER_IMPL_H_
 #define WEBRTC_MODULES_RTP_RTCP_SOURCE_FEC_RECEIVER_IMPL_H_
 
 // This header is included to get the nested declaration of Packet structure.
 
 #include "webrtc/base/scoped_ptr.h"
 #include "webrtc/modules/rtp_rtcp/include/fec_receiver.h"
 #include "webrtc/modules/rtp_rtcp/include/rtp_rtcp_defines.h"
 #include "webrtc/modules/rtp_rtcp/source/forward_error_correction.h"
 #include "webrtc/typedefs.h"
 
 namespace webrtc {
 
 class CriticalSectionWrapper;
 
 class FecReceiverImpl : public FecReceiver {
  public:
-  FecReceiverImpl(RtpData* callback);
+  explicit FecReceiverImpl(RtpData* callback);
   virtual ~FecReceiverImpl();
 
   int32_t AddReceivedRedPacket(const RTPHeader& rtp_header,
                                const uint8_t* incoming_rtp_packet,
                                size_t packet_length,
                                uint8_t ulpfec_payload_type) override;
 
   int32_t ProcessReceivedFec() override;
 
   FecPacketCounter GetPacketCounter() const override;
 
  private:
   rtc::scoped_ptr<CriticalSectionWrapper> crit_sect_;
   RtpData* recovered_packet_callback_;
   ForwardErrorCorrection* fec_;
   // TODO(holmer): In the current version received_packet_list_ is never more
   // than one packet, since we process FEC every time a new packet
   // arrives. We should remove the list.
   ForwardErrorCorrection::ReceivedPacketList received_packet_list_;
   ForwardErrorCorrection::RecoveredPacketList recovered_packet_list_;
   FecPacketCounter packet_counter_;
 };
 }  // namespace webrtc
 
 #endif  // WEBRTC_MODULES_RTP_RTCP_SOURCE_FEC_RECEIVER_IMPL_H_