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

ui/ozone/platform/dri/screen_manager.h

Index: ui/ozone/platform/dri/screen_manager.h
diff --git a/ui/ozone/platform/dri/screen_manager.h b/ui/ozone/platform/dri/screen_manager.h
index 5eaae1aafa6a535e89c5980c7a478060e93aa535..22ea14a91ec4c98863480f5b80dd2a1563abc65f 100644
--- a/ui/ozone/platform/dri/screen_manager.h
+++ b/ui/ozone/platform/dri/screen_manager.h
@@ -8,6 +8,7 @@
 #include "base/macros.h"
 #include "base/memory/scoped_vector.h"
 #include "base/observer_list.h"
+#include "ui/ozone/ozone_export.h"
 #include "ui/ozone/platform/dri/display_change_observer.h"
 #include "ui/ozone/platform/dri/hardware_display_controller.h"
 
@@ -25,7 +26,7 @@ class DriWrapper;
 class ScanoutBufferGenerator;
 
 // Responsible for keeping track of active displays and configuring them.
-class ScreenManager {
+class OZONE_EXPORT ScreenManager {
  public:
   ScreenManager(DriWrapper* dri, ScanoutBufferGenerator* surface_generator);
   virtual ~ScreenManager();