Remove OnApplicationClose upcalls, update OnConnectionClose as needed.

Replaces the OnApplicationClose visitor upcalls with OnConnectionClose. The IETF removes the separate Application Close frame from QUIC, modifying the Connection Close frame to have two flavors; one for Application-initiated reasons, the other for Transport reasons. These were formerly the Application- and Connection- closes.

gfe-relnote: N/A this is only for IETF QUIC (version 99).
PiperOrigin-RevId: 243856589
Change-Id: Ie048aa2a8641f7e3f84b6cd7e4fc6ce61d5683e7
diff --git a/quic/core/quic_connection_test.cc b/quic/core/quic_connection_test.cc
index 4072ecd..56b0453 100644
--- a/quic/core/quic_connection_test.cc
+++ b/quic/core/quic_connection_test.cc
@@ -1368,6 +1368,8 @@
 
     QuicConnectionCloseFrame qccf(QUIC_PEER_GOING_AWAY);
     if (peer_framer_.transport_version() == QUIC_VERSION_99) {
+      // Default close-type is Google QUIC. If doing IETF/V99 then
+      // set close type to be IETF CC/T.
       qccf.close_type = IETF_QUIC_TRANSPORT_CONNECTION_CLOSE;
     }
 
@@ -7233,6 +7235,8 @@
 
   QuicConnectionCloseFrame qccf(QUIC_PEER_GOING_AWAY);
   if (peer_framer_.transport_version() == QUIC_VERSION_99) {
+    // Default close-type is Google QUIC. If doing IETF/V99 then
+    // set close type to be IETF CC/T.
     qccf.close_type = IETF_QUIC_TRANSPORT_CONNECTION_CLOSE;
   }