Minor FlexFEC fixes.

webrtc/modules/rtp_rtcp/include/flexfec_sender.h

 /*
  *  Copyright (c) 2016 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.
  */
 
@@ skipping 12 matching lines @@
 #include "webrtc/modules/rtp_rtcp/source/rtp_header_extension.h"
 #include "webrtc/modules/rtp_rtcp/source/rtp_packet_to_send.h"
 #include "webrtc/modules/rtp_rtcp/source/ulpfec_generator.h"
 #include "webrtc/system_wrappers/include/clock.h"
 
 namespace webrtc {
 
 class RtpPacketToSend;
 
 // Note that this class is not thread safe, and thus requires external
-// synchronization.
+// synchronization. Currently, this is done using the lock in PayloadRouter.
 
 class FlexfecSender {
  public:
   FlexfecSender(int payload_type,
                 uint32_t ssrc,
                 uint32_t protected_media_ssrc,
                 const std::vector<RtpExtension>& rtp_header_extensions,
                 Clock* clock);
   ~FlexfecSender();
 
@@ skipping 33 matching lines @@
   uint16_t seq_num_;
 
   // Implementation.
   UlpfecGenerator ulpfec_generator_;
   const RtpHeaderExtensionMap rtp_header_extension_map_;
 };
 
 }  // namespace webrtc
 
 #endif  // WEBRTC_MODULES_RTP_RTCP_INCLUDE_FLEXFEC_SENDER_H_