Support subtitles for native fullscreen video

Source/core/rendering/RenderLayerCompositor.h

Index: Source/core/rendering/RenderLayerCompositor.h
diff --git a/Source/core/rendering/RenderLayerCompositor.h b/Source/core/rendering/RenderLayerCompositor.h
index 3496bddea74c878e16b32d8dd26167cac9c3bee6..f7ee39d64e61e58919dbdc9d7d20a16743d291b6 100644
--- a/Source/core/rendering/RenderLayerCompositor.h
+++ b/Source/core/rendering/RenderLayerCompositor.h
@@ -206,6 +206,9 @@ public:
 
     virtual String debugName(const GraphicsLayer*) OVERRIDE;
 
+    // Only called for main frame. Input object can be cross frame.
+    void setCurrentFullscreenRenderer(RenderObject*);

[esprehn, 2013/09/13 02:46:07]

This doesn't look safe at all, passing a RenderObject between frames creates
really scary looking conditions where one frame goes through a styleRecalc and
the cleanup is not correct here and now you have a use-after-free.

[trchen, 2013/09/13 05:14:58]

See answer in RLC.cpp

+
 private:
     class OverlapMap;
 
@@ -354,6 +357,8 @@ private:
     OwnPtr<GraphicsLayer> m_layerForOverhangShadow;
 #endif
 
+    RenderObject* m_currentFullscreenRenderer;
+
 #if !LOG_DISABLED
     int m_rootLayerUpdateCount;
     int m_obligateCompositedLayerCount; // count of layer that have to be composited.