Log how often DTLS negotiation failed because of incompatible ciphersuites.

webrtc/p2p/base/dtlstransportchannel.h

 /*
  *  Copyright 2011 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 203 matching lines @@
   void OnCandidatesRemoved(TransportChannelImpl* channel,
                            const Candidates& candidates);
   void OnRoleConflict(TransportChannelImpl* channel);
   void OnRouteChange(TransportChannel* channel, const Candidate& candidate);
   void OnSelectedCandidatePairChanged(
       TransportChannel* channel,
       CandidatePairInterface* selected_candidate_pair,
       int last_sent_packet_id,
       bool ready_to_send);
   void OnChannelStateChanged(TransportChannelImpl* channel);
+  void OnDtlsHandshakeError(rtc::SSLHandshakeError error);
 
   rtc::Thread* worker_thread_;  // Everything should occur on this thread.
   // Underlying channel, not owned by this class.
   TransportChannelImpl* const channel_;
   std::unique_ptr<rtc::SSLStreamAdapter> dtls_;  // The DTLS stream
   StreamInterfaceChannel* downward_;  // Wrapper for channel_, owned by dtls_.
   std::vector<int> srtp_ciphers_;     // SRTP ciphers to use with DTLS.
   bool dtls_active_ = false;
   rtc::scoped_refptr<rtc::RTCCertificate> local_certificate_;
   rtc::SSLRole ssl_role_;
   rtc::SSLProtocolVersion ssl_max_version_;
   rtc::Buffer remote_fingerprint_value_;
   std::string remote_fingerprint_algorithm_;
 
   // Cached DTLS ClientHello packet that was received before we started the
   // DTLS handshake. This could happen if the hello was received before the
   // transport channel became writable, or before a remote fingerprint was
   // received.
   rtc::Buffer cached_client_hello_;
 
   RTC_DISALLOW_COPY_AND_ASSIGN(DtlsTransportChannelWrapper);
 };
 
 }  // namespace cricket
 
 #endif  // WEBRTC_P2P_BASE_DTLSTRANSPORTCHANNEL_H_