Adds missing include.

net/quic/quartc/quartc_stream_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_STREAM_INTERFACE_H_
 #define NET_QUIC_QUARTC_QUARTC_STREAM_INTERFACE_H_
 
 #include <stddef.h>
 #include <stdint.h>
 
+#include "net/quic/platform/api/quic_export.h"
+
 namespace net {
 
 // Sends and receives data with a particular QUIC stream ID, reliably and
 // in-order. To send/receive data out of order, use separate streams. To
 // send/receive unreliably, close a stream after reliability is no longer
 // needed.
 class QUIC_EXPORT_PRIVATE QuartcStreamInterface {
  public:
   virtual ~QuartcStreamInterface() {}
 
@@ skipping 50 matching lines @@
     virtual void OnBufferedAmountDecrease(QuartcStreamInterface* stream) = 0;
   };
 
   // The |delegate| is not owned by QuartcStream.
   virtual void SetDelegate(Delegate* delegate) = 0;
 };
 
 }  // namespace net
 
 #endif  // NET_QUIC_QUARTC_QUARTC_STREAM_INTERFACE_H_