Adds missing include.

net/quic/quartc/quartc_session_interface.h

 // Copyright (c) 2017 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_QUARTC_QUARTC_SESSION_INTERFACE_H_
 #define NET_QUIC_QUARTC_QUARTC_SESSION_INTERFACE_H_
 
 #include <stddef.h>
 #include <stdint.h>
 #include <string>
 
 #include "net/quic/core/quic_error_codes.h"
 #include "net/quic/core/quic_types.h"
+#include "net/quic/platform/api/quic_export.h"
 #include "net/quic/quartc/quartc_stream_interface.h"
 
 namespace net {
 
 // Given a PacketTransport, provides a way to send and receive separate streams
 // of reliable, in-order, encrypted data. For example, this can build on top of
 // a WebRTC IceTransport for sending and receiving data over QUIC.
 class QUIC_EXPORT_PRIVATE QuartcSessionInterface {
  public:
   virtual ~QuartcSessionInterface() {}
@@ skipping 77 matching lines @@
     // TODO(zhihuang): Add proof verification.
   };
 
   // The |delegate| is not owned by QuartcSession.
   virtual void SetDelegate(Delegate* delegate) = 0;
 };
 
 }  // namespace net
 
 #endif  // NET_QUIC_QUARTC_QUARTC_SESSION_INTERFACE_H_