ozone: dri: Fix undefined references in DRI platform GN build

ui/ozone/platform/dri/dri_buffer.h

 // Copyright 2014 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 UI_OZONE_PLATFORM_DRI_DRI_BUFFER_H_
 #define UI_OZONE_PLATFORM_DRI_DRI_BUFFER_H_
 
 #include "base/macros.h"
 #include "skia/ext/refptr.h"
 #include "third_party/skia/include/core/SkSurface.h"
+#include "ui/ozone/ozone_export.h"
 #include "ui/ozone/platform/dri/scanout_buffer.h"
 
 namespace ui {
 
 class DriWrapper;
 
 // Wrapper for a DRM allocated buffer. Keeps track of the native properties of
 // the buffer and wraps the pixel memory into a SkSurface which can be used to
 // draw into using Skia.
-class DriBuffer : public ScanoutBuffer {
+class OZONE_EXPORT DriBuffer : public ScanoutBuffer {
  public:
   DriBuffer(DriWrapper* dri);
 
   // Allocates the backing pixels and wraps them in |surface_|. |info| is used
   // to describe the buffer characteristics (size, color format).
   bool Initialize(const SkImageInfo& info);
 
   SkCanvas* GetCanvas() const;
 
   // ScanoutBuffer:
@@ skipping 15 matching lines @@
   // Buffer handle used by the DRM allocator.
   uint32_t handle_;
 
   // Buffer ID used by the DRM modesettings API. This is set when the buffer is
   // registered with the CRTC.
   uint32_t framebuffer_;
 
   DISALLOW_COPY_AND_ASSIGN(DriBuffer);
 };
 
-class DriBufferGenerator : public ScanoutBufferGenerator {
+class OZONE_EXPORT DriBufferGenerator : public ScanoutBufferGenerator {
  public:
   DriBufferGenerator();
   ~DriBufferGenerator() override;
 
   // ScanoutBufferGenerator:
   scoped_refptr<ScanoutBuffer> Create(DriWrapper* drm,
                                       const gfx::Size& size) override;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(DriBufferGenerator);
 };
 
 }  // namespace ui
 
 #endif  // UI_OZONE_PLATFORM_DRI_DRI_BUFFER_H_