Add a new GetNegotiatedProtocol method to StreamSocket and implement in all subclasses.

net/socket/tcp_client_socket_win.cc

Index: net/socket/tcp_client_socket_win.cc
diff --git a/net/socket/tcp_client_socket_win.cc b/net/socket/tcp_client_socket_win.cc
index 196522db25dbbfe2dce0fa074bf58b3c2322fe52..28b0eeffbb3fbf0e8b207fd7dbc41f1120fcf756 100644
--- a/net/socket/tcp_client_socket_win.cc
+++ b/net/socket/tcp_client_socket_win.cc
@@ -674,6 +674,10 @@ base::TimeDelta TCPClientSocketWin::GetConnectTimeMicros() const {
   return connect_time_micros_;
 }
 
+NextProto TCPClientSocketWin::GetNegotiatedProtocol() const {
+  return kProtoUnknown;
+}
+
 int TCPClientSocketWin::Read(IOBuffer* buf,
                              int buf_len,
                              const CompletionCallback& callback) {