Replace QuicUnorderedMap and QuicHashMap with the corresponding Abseil classes.

Chromium has been using Abseil for those since September, so it should be safe
to switch.

PiperOrigin-RevId: 355221659
Change-Id: I0c1006c193554f71745234ba4b90eafc8ff30ed9
diff --git a/quic/masque/masque_dispatcher.h b/quic/masque/masque_dispatcher.h
index 59fc068..2e0186c 100644
--- a/quic/masque/masque_dispatcher.h
+++ b/quic/masque/masque_dispatcher.h
@@ -5,6 +5,7 @@
 #ifndef QUICHE_QUIC_MASQUE_MASQUE_DISPATCHER_H_
 #define QUICHE_QUIC_MASQUE_MASQUE_DISPATCHER_H_
 
+#include "absl/container/flat_hash_map.h"
 #include "quic/masque/masque_server_backend.h"
 #include "quic/masque/masque_server_session.h"
 #include "quic/platform/api/quic_export.h"
@@ -53,7 +54,9 @@
   MasqueServerBackend* masque_server_backend_;  // Unowned.
   // Mapping from client connection IDs to server sessions, allows routing
   // incoming packets to the right MASQUE connection.
-  QuicHashMap<QuicConnectionId, MasqueServerSession*, QuicConnectionIdHash>
+  absl::flat_hash_map<QuicConnectionId,
+                      MasqueServerSession*,
+                      QuicConnectionIdHash>
       client_connection_id_registrations_;
 };