Fix net_export.h includes.

net/quic/core/quic_packet_writer.h

 // Copyright 2013 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.
 
 #ifndef NET_QUIC_QUIC_PACKET_WRITER_H_
 #define NET_QUIC_QUIC_PACKET_WRITER_H_
 
 #include <stddef.h>
 
 #include "net/base/ip_endpoint.h"
+#include "net/base/net_export.h"
 #include "net/quic/core/quic_protocol.h"
 
 namespace net {
 
 class IPAddress;
 struct WriteResult;
 
 class NET_EXPORT_PRIVATE PerPacketOptions {
  public:
   PerPacketOptions() = default;
@@ skipping 43 matching lines @@
   // Returns the maximum size of the packet which can be written using this
   // writer for the supplied peer address.  This size may actually exceed the
   // size of a valid QUIC packet.
   virtual QuicByteCount GetMaxPacketSize(
       const IPEndPoint& peer_address) const = 0;
 };
 
 }  // namespace net
 
 #endif  // NET_QUIC_QUIC_PACKET_WRITER_H_