In QUIC, use using for alias declaration.

This is the preferred way according to go/cstyle#Aliases

PiperOrigin-RevId: 341926282
Change-Id: Ib70cdb37fbdc985dec9e862c60aacbae54510281
diff --git a/quic/test_tools/packet_dropping_test_writer.h b/quic/test_tools/packet_dropping_test_writer.h
index 02eebe9..01a07ce 100644
--- a/quic/test_tools/packet_dropping_test_writer.h
+++ b/quic/test_tools/packet_dropping_test_writer.h
@@ -157,7 +157,7 @@
     QuicTime send_time;
   };
 
-  typedef std::list<DelayedWrite> DelayedPacketList;
+  using DelayedPacketList = std::list<DelayedWrite>;
 
   const QuicClock* clock_;
   std::unique_ptr<QuicAlarm> write_unblocked_alarm_;