Use sockets with unread data if they've never been used before.

net/socket/ssl_client_socket_openssl.h

 // 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.
 
 #ifndef NET_SOCKET_SSL_CLIENT_SOCKET_OPENSSL_H_
 #define NET_SOCKET_SSL_CLIENT_SOCKET_OPENSSL_H_
 
 #include <string>
 
 #include "base/compiler_specific.h"
@@ skipping 155 matching lines @@
 
   // Used by TransportWriteComplete() and TransportReadComplete() to signify an
   // error writing to the transport socket. A value of OK indicates no error.
   int transport_write_error_;
 
   // Set when handshake finishes.
   scoped_refptr<X509Certificate> server_cert_;
   CertVerifyResult server_cert_verify_result_;
   bool completed_handshake_;
 
+  // Set when Read() or Write() successfully reads or writes data to or from the
+  // network.
+  bool was_used_to_convey_data_;
+
   // Stores client authentication information between ClientAuthHandler and
   // GetSSLCertRequestInfo calls.
   bool client_auth_cert_needed_;
   // List of DER-encoded X.509 DistinguishedName of certificate authorities
   // allowed by the server.
   std::vector<std::string> cert_authorities_;
 
   CertVerifier* const cert_verifier_;
   scoped_ptr<SingleRequestCertVerifier> verifier_;
 
@@ skipping 33 matching lines @@
   // True if channel ID extension was negotiated.
   bool channel_id_xtn_negotiated_;
   // The request handle for |server_bound_cert_service_|.
   ServerBoundCertService::RequestHandle channel_id_request_handle_;
   BoundNetLog net_log_;
 };
 
 }  // namespace net
 
 #endif  // NET_SOCKET_SSL_CLIENT_SOCKET_OPENSSL_H_