Merging to M57 branch 2987.

third_party/WebKit/Source/modules/peerconnection/RTCPeerConnection.cpp

Index: third_party/WebKit/Source/modules/peerconnection/RTCPeerConnection.cpp
diff --git a/third_party/WebKit/Source/modules/peerconnection/RTCPeerConnection.cpp b/third_party/WebKit/Source/modules/peerconnection/RTCPeerConnection.cpp
index f43775ef8786494f1dd7ecf39eb99ff3ed3f37ed..50c28cbe1bca6eae71dbd6129a473444e2c6403e 100644
--- a/third_party/WebKit/Source/modules/peerconnection/RTCPeerConnection.cpp
+++ b/third_party/WebKit/Source/modules/peerconnection/RTCPeerConnection.cpp
@@ -46,6 +46,7 @@
 #include "core/dom/Document.h"
 #include "core/dom/ExceptionCode.h"
 #include "core/dom/ExecutionContext.h"
+#include "core/frame/Deprecation.h"
 #include "core/frame/HostsUsingFeatures.h"
 #include "core/frame/LocalFrame.h"
 #include "core/frame/UseCounter.h"
@@ -263,6 +264,7 @@ WebRTCConfiguration parseConfiguration(ExecutionContext* context,
   String rtcpMuxPolicyString = configuration.rtcpMuxPolicy();
   if (rtcpMuxPolicyString == "negotiate") {
     rtcpMuxPolicy = WebRTCRtcpMuxPolicy::kNegotiate;
+    Deprecation::countDeprecation(context, UseCounter::RtcpMuxPolicyNegotiate);
   } else {
     DCHECK_EQ(rtcpMuxPolicyString, "require");
   }