Add a placeholder stat for logging the estimated residual echo likelihood.

webrtc/api/statstypes.h

 /*
  *  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 180 matching lines @@
     kStatsValueNameNacksSent,
     kStatsValueNamePlisReceived,
     kStatsValueNamePlisSent,
     kStatsValueNamePreemptiveExpandRate,
     kStatsValueNamePreferredJitterBufferMs,
     kStatsValueNameRemoteAddress,
     kStatsValueNameRemoteCandidateId,
     kStatsValueNameRemoteCandidateType,
     kStatsValueNameRemoteCertificateId,
     kStatsValueNameRenderDelayMs,
+    kStatsValueNameResidualEchoLikelihood,
     kStatsValueNameRetransmitBitrate,
     kStatsValueNameRtt,
     kStatsValueNameSecondaryDecodedRate,
     kStatsValueNameSendPacketsDiscarded,
     kStatsValueNameSpeechExpandRate,
     kStatsValueNameSrtpCipher,
     kStatsValueNameTargetDelayMs,
     kStatsValueNameTargetEncBitrate,
     kStatsValueNameTrackId,
     kStatsValueNameTransmitBitrate,
@@ skipping 189 matching lines @@
   StatsReport* Find(const StatsReport::Id& id);
 
  private:
   Container list_;
   rtc::ThreadChecker thread_checker_;
 };
 
 }  // namespace webrtc
 
 #endif  // WEBRTC_API_STATSTYPES_H_