1 files changed, 3 insertions, 0 deletions
diff --git a/gfx/2d/2D.h b/gfx/2d/2D.h
index c1fba3463..e2020dc9e 100644
--- a/gfx/2d/2D.h
+++ b/gfx/2d/2D.h
@@ -488,6 +488,9 @@ public:
   /**
    * Returns a DataSourceSurface with the same data as this one, but
    * guaranteed to have surface->GetType() == SurfaceType::DATA.
+   *
+   * The returning surface might be null, because of OOM or gfx device reset.
+   * The caller needs to do null-check before using it.
    */
   virtual already_AddRefed<DataSourceSurface> GetDataSurface() override;