use std::unordered_map and std::unordered_set in QUIC code instead of

net/quic/quic_packet_creator.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "net/quic/quic_packet_creator.h"
 
 #include <algorithm>
 
 #include "base/logging.h"
 #include "base/macros.h"
@@ skipping 831 matching lines @@
   if (HasPendingFrames()) {
     QUIC_BUG << "Unable to change paths when a packet is under construction.";
     return;
   }
 
   // Send FEC packet and close FEC group.
   MaybeSendFecPacketAndCloseGroup(/*force_send_fec=*/true,
                                   /*is_fec_timeout=*/false);
   // Save current packet number and load switching path's packet number.
   multipath_packet_number_[packet_.path_id] = packet_.packet_number;
-  hash_map<QuicPathId, QuicPacketNumber>::iterator it =
+  std::unordered_map<QuicPathId, QuicPacketNumber>::iterator it =
       multipath_packet_number_.find(path_id);
   // If path_id is not in the map, it's a new path. Set packet_number to 0.
   packet_.packet_number = it == multipath_packet_number_.end() ? 0 : it->second;
   packet_.path_id = path_id;
   DCHECK(packet_.path_id != kInvalidPathId);
   // Send path in packet if current path is not the default path.
   send_path_id_in_packet_ = packet_.path_id != kDefaultPathId ? true : false;
   // Switching path needs to update packet number length.
   UpdatePacketNumberLength(least_packet_awaited_by_peer, max_packets_in_flight);
 }
 
 }  // namespace net