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

net/socket/stream_socket.h

Index: net/socket/stream_socket.h
diff --git a/net/socket/stream_socket.h b/net/socket/stream_socket.h
index d9fee24cebb9642314e08cb2ff05ad54fde27a1c..4d7b7e28260f86a57aac63509b90d20bfa577624 100644
--- a/net/socket/stream_socket.h
+++ b/net/socket/stream_socket.h
@@ -87,6 +87,10 @@ class NET_EXPORT_PRIVATE StreamSocket : public Socket {
   // Returns the connection setup time of this socket.
   virtual base::TimeDelta GetConnectTimeMicros() const = 0;
 
+  // Returns the protocol negotiated via NPN for this socket, or
+  // kProtoUnknown will be returned if NPN is not applicable.
+  virtual NextProto GetNegotiatedProtocol() const = 0;
+
  protected:
   // The following class is only used to gather statistics about the history of
   // a socket.  It is only instantiated and used in basic sockets, such as