Adds missing include.

net/quic/quartc/quartc_stream.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_STREAM_H_
 #define NET_QUIC_QUARTC_QUARTC_STREAM_H_
 
 #include "net/quic/core/quic_session.h"
 #include "net/quic/core/quic_stream.h"
+#include "net/quic/platform/api/quic_export.h"
 #include "net/quic/quartc/quartc_stream_interface.h"
 
 namespace net {
 
 // Implements a QuartcStreamInterface using a QuicStream.
 class QUIC_EXPORT_PRIVATE QuartcStream : public QuicStream,
                                          public QuartcStreamInterface {
  public:
   QuartcStream(QuicStreamId id, QuicSession* session);
 
@@ skipping 25 matching lines @@
 
   void SetDelegate(QuartcStreamInterface::Delegate* delegate) override;
 
  private:
   QuartcStreamInterface::Delegate* delegate_ = nullptr;
 };
 
 }  // namespace net
 
 #endif  // NET_QUIC_QUARTC_QUARTC_STREAM_H_