Rename connection_id to server_connection_id

This is a step on the way to enabling client connection IDs. It will make the code less ambiguous once we introduce client_connection_id.

gfe-relnote: n/a, renaming code only
PiperOrigin-RevId: 249045070
Change-Id: Ia7ba75511f96c896bc6f0f4978dae2cd13e707fb
diff --git a/quic/core/quic_session.h b/quic/core/quic_session.h
index d8f40c9..dc7153a 100644
--- a/quic/core/quic_session.h
+++ b/quic/core/quic_session.h
@@ -52,7 +52,7 @@
     virtual ~Visitor() {}
 
     // Called when the connection is closed after the streams have been closed.
-    virtual void OnConnectionClosed(QuicConnectionId connection_id,
+    virtual void OnConnectionClosed(QuicConnectionId server_connection_id,
                                     QuicErrorCode error,
                                     const std::string& error_details,
                                     ConnectionCloseSource source) = 0;