Convert Ozone GL OSMesa implementation.

ui/ozone/platform/drm/gpu/gbm_surface_factory.h

Index: ui/ozone/platform/drm/gpu/gbm_surface_factory.h
diff --git a/ui/ozone/platform/drm/gpu/gbm_surface_factory.h b/ui/ozone/platform/drm/gpu/gbm_surface_factory.h
index aaf50542adc3e4b768468b902132662a43349e7b..48f429c41ec1673bd45ece78fc7206140c9248ed 100644
--- a/ui/ozone/platform/drm/gpu/gbm_surface_factory.h
+++ b/ui/ozone/platform/drm/gpu/gbm_surface_factory.h
@@ -53,6 +53,7 @@ class GbmSurfaceFactory : public SurfaceFactoryOzone {
 
  private:
   std::unique_ptr<GLOzone> egl_implementation_;
+  std::unique_ptr<GLOzone> osmesa_implementation_;
 
   base::ThreadChecker thread_checker_;