Disentangle filter content recording state from FilterData

Source/core/paint/SVGFilterPainter.h

Index: Source/core/paint/SVGFilterPainter.h
diff --git a/Source/core/paint/SVGFilterPainter.h b/Source/core/paint/SVGFilterPainter.h
index 1d6768d714da552014f4c87b286507cf456b9299..94a968e5975f74410b6fa9fd414e5a3dbc0a1bbc 100644
--- a/Source/core/paint/SVGFilterPainter.h
+++ b/Source/core/paint/SVGFilterPainter.h
@@ -5,20 +5,39 @@
 #ifndef SVGFilterPainter_h
 #define SVGFilterPainter_h
 
+#include "platform/graphics/GraphicsContext.h"
+#include "platform/graphics/paint/DisplayItemList.h"
+#include "wtf/OwnPtr.h"
+
 namespace blink {
 
-class GraphicsContext;
+class FilterData;
 class LayoutObject;
 class LayoutSVGResourceFilter;
 
+class SVGFilterRecordingContext {
+public:
+    explicit SVGFilterRecordingContext(GraphicsContext* initialContext) : m_initialContext(initialContext) { }
+
+    GraphicsContext* beginContent(FilterData*);
+    void endContent(FilterData*);
+
+    GraphicsContext* paintingContext() const { return m_initialContext; }
+
+private:
+    OwnPtr<DisplayItemList> m_displayItemList;
+    OwnPtr<GraphicsContext> m_context;
+    GraphicsContext* m_initialContext;
+};
+
 class SVGFilterPainter {
 public:
     SVGFilterPainter(LayoutSVGResourceFilter& filter) : m_filter(filter) { }
 
     // Returns the context that should be used to paint the filter contents, or
     // null if the content should not be recorded.
-    GraphicsContext* prepareEffect(LayoutObject&, GraphicsContext*);
-    void finishEffect(LayoutObject&, GraphicsContext*);
+    GraphicsContext* prepareEffect(LayoutObject&, SVGFilterRecordingContext&);
+    void finishEffect(LayoutObject&, SVGFilterRecordingContext&);
 
 private:
     LayoutSVGResourceFilter& m_filter;