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_framer.h b/quic/core/quic_framer.h
index ab0e8d7..e56aba2 100644
--- a/quic/core/quic_framer.h
+++ b/quic/core/quic_framer.h
@@ -441,7 +441,7 @@
 
   // Returns a new IETF version negotiation packet.
   static std::unique_ptr<QuicEncryptedPacket> BuildIetfVersionNegotiationPacket(
-      QuicConnectionId connection_id,
+      QuicConnectionId source_connection_id,
       const ParsedQuicVersionVector& versions);
 
   // If header.version_flag is set, the version in the
@@ -958,8 +958,8 @@
   // Largest successfully decrypted packet number per packet number space. Only
   // used when supports_multiple_packet_number_spaces_ is true.
   QuicPacketNumber largest_decrypted_packet_numbers_[NUM_PACKET_NUMBER_SPACES];
-  // Updated by WritePacketHeader.
-  QuicConnectionId last_serialized_connection_id_;
+  // Last server connection ID seen on the wire.
+  QuicConnectionId last_serialized_server_connection_id_;
   // The last QUIC version label received.
   // TODO(fayang): Remove this when deprecating
   // quic_no_framer_object_in_dispatcher.