Add a CHECK to help track down the crash in http://crbug.com/49862....

net/socket/ssl_client_socket_nss.cc

 // Copyright (c) 2010 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.
 
 // This file includes code SSLClientSocketNSS::DoVerifyCertComplete() derived
 // from AuthCertificateCallback() in
 // mozilla/security/manager/ssl/src/nsNSSCallbacks.cpp.
 
 /* ***** BEGIN LICENSE BLOCK *****
  * Version: MPL 1.1/GPL 2.0/LGPL 2.1
@@ skipping 750 matching lines @@
       !received_renego_info) {
     LOG(INFO) << "The server " << hostname_
               << " does not support the TLS renegotiation_info extension.";
   }
 #endif
 }
 
 void SSLClientSocketNSS::GetSSLInfo(SSLInfo* ssl_info) {
   EnterFunction("");
   ssl_info->Reset();
+  // A temporary CHECK for tracking down http://crbug.com/49862.
+  CHECK(server_cert_);
   if (!server_cert_)
     return;
 
   SSLChannelInfo channel_info;
   SECStatus ok = SSL_GetChannelInfo(nss_fd_,
                                     &channel_info, sizeof(channel_info));
   if (ok == SECSuccess &&
       channel_info.length == sizeof(channel_info) &&
       channel_info.cipherSuite) {
     SSLCipherSuiteInfo cipher_info;
@@ skipping 785 matching lines @@
   PRErrorCode prerr = PR_GetError();
   if (prerr == PR_WOULD_BLOCK_ERROR) {
     LeaveFunction("");
     return ERR_IO_PENDING;
   }
   LeaveFunction("");
   return MapNSPRError(prerr);
 }
 
 }  // namespace net