Support subtitles for native fullscreen video

Source/core/rendering/RenderView.h

Index: Source/core/rendering/RenderView.h
diff --git a/Source/core/rendering/RenderView.h b/Source/core/rendering/RenderView.h
index 5ac228eded52bd391d5a172982d81cd32230f22a..703e95c1f432eaa26496ad1f22a2000f5ac60232 100644
--- a/Source/core/rendering/RenderView.h
+++ b/Source/core/rendering/RenderView.h
@@ -214,6 +214,9 @@ public:
     LayoutUnit viewportPercentageMin(float percentage) const;
     LayoutUnit viewportPercentageMax(float percentage) const;
 
+    // Only called for main frame. Input object can be cross frame.
+    void setCurrentFullscreenRenderer(RenderObject*);
+
 private:
     virtual void mapLocalToContainer(const RenderLayerModelObject* repaintContainer, TransformState&, MapCoordinatesFlags = ApplyContainerFlip, bool* wasFixed = 0) const OVERRIDE;
     virtual const RenderObject* pushMappingToContainer(const RenderLayerModelObject* ancestorToStopAt, RenderGeometryMap&) const OVERRIDE;