Add a histogram for session resumption version mismatches.

net/socket/ssl_client_socket_openssl.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // OpenSSL binding for SSLClientSocket. The class layout and general principle
 // of operation is derived from SSLClientSocketNSS.
 
 #include "net/socket/ssl_client_socket_openssl.h"
 
 #include <errno.h>
@@ skipping 1113 matching lines @@
   if (!start_cert_verification_time_.is_null()) {
     base::TimeDelta verify_time =
         base::TimeTicks::Now() - start_cert_verification_time_;
     if (result == OK) {
       UMA_HISTOGRAM_TIMES("Net.SSLCertVerificationTime", verify_time);
     } else {
       UMA_HISTOGRAM_TIMES("Net.SSLCertVerificationTimeError", verify_time);
     }
   }
 
-  if (result == OK)
+  if (result == OK) {
     RecordConnectionTypeMetrics(GetNetSSLVersion(ssl_));
 
+    if (SSL_session_reused(ssl_)) {
+      // Record whether or not the server tried to resume a session for a
+      // different version. See https://crbug.com/441456.
+      UMA_HISTOGRAM_BOOLEAN(
+          "Net.SSLSessionVersionMatch",
+          SSL_version(ssl_) == SSL_get_session(ssl_)->ssl_version);
+    }
+  }
+
   const CertStatus cert_status = server_cert_verify_result_.cert_status;
   if (transport_security_state_ &&
       (result == OK ||
        (IsCertificateError(result) && IsCertStatusMinorError(cert_status))) &&
       !transport_security_state_->CheckPublicKeyPins(
           host_and_port_.host(),
           server_cert_verify_result_.is_issued_by_known_root,
           server_cert_verify_result_.public_key_hashes,
           &pinning_failure_log_)) {
     result = ERR_SSL_PINNED_KEY_NOT_IN_CERT_CHAIN;
@@ skipping 756 matching lines @@
                                             ct::SCT_STATUS_LOG_UNKNOWN));
   }
 }
 
 scoped_refptr<X509Certificate>
 SSLClientSocketOpenSSL::GetUnverifiedServerCertificateChain() const {
   return server_cert_;
 }
 
 }  // namespace net