Log how often DTLS negotiation failed because of incompatible ciphersuites.

webrtc/api/webrtcsession.cc

 /*
  *  Copyright 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.
  */
 
@@ skipping 475 matching lines @@
   transport_controller_->SignalConnectionState.connect(
       this, &WebRtcSession::OnTransportControllerConnectionState);
   transport_controller_->SignalReceiving.connect(
       this, &WebRtcSession::OnTransportControllerReceiving);
   transport_controller_->SignalGatheringState.connect(
       this, &WebRtcSession::OnTransportControllerGatheringState);
   transport_controller_->SignalCandidatesGathered.connect(
       this, &WebRtcSession::OnTransportControllerCandidatesGathered);
   transport_controller_->SignalCandidatesRemoved.connect(
       this, &WebRtcSession::OnTransportControllerCandidatesRemoved);
+  transport_controller_->SignalDtlsHandshakeError.connect(
+      this, &WebRtcSession::OnDtlsHandshakeError);
 }
 
 WebRtcSession::~WebRtcSession() {
   ASSERT(signaling_thread()->IsCurrent());
   // Destroy video_channel_ first since it may have a pointer to the
   // voice_channel_.
   if (video_channel_) {
     SignalVideoChannelDestroyed();
     channel_manager_->DestroyVideoChannel(video_channel_.release());
   }
@@ skipping 1560 matching lines @@
     if (data_channel_type_ == cricket::DCT_QUIC && quic_data_transport_ &&
         content_name == quic_data_transport_->transport_name()) {
       return quic_data_transport_->transport_name();
     }
 #endif
     // Return an empty string if failed to retrieve the transport name.
     return "";
   }
   return channel->transport_name();
 }
+
+void WebRtcSession::OnDtlsHandshakeError(rtc::SSLHandshakeError error) {
+  if (metrics_observer_) {
+    metrics_observer_->IncrementEnumCounter(
+        webrtc::kEnumCounterDtlsHandshakeError, static_cast<int>(error),
+        static_cast<int>(rtc::SSLHandshakeError::MAX_VALUE));
+  }
+}
 }  // namespace webrtc