Allow certain SP recorder classes to defer their "begin" operation.

Source/core/paint/RoundedInnerRectClipper.h

Index: Source/core/paint/RoundedInnerRectClipper.h
diff --git a/Source/core/paint/RoundedInnerRectClipper.h b/Source/core/paint/RoundedInnerRectClipper.h
index d400b43156d05b900d4831464bf727f28f700b59..d9636a7d644bed88ec77999807bbc73706eb801d 100644
--- a/Source/core/paint/RoundedInnerRectClipper.h
+++ b/Source/core/paint/RoundedInnerRectClipper.h
@@ -21,14 +21,21 @@ enum RoundedInnerRectClipperBehavior {
 
 class RoundedInnerRectClipper {
 public:
+    RoundedInnerRectClipper(LayoutObject&, const PaintInfo&);
     RoundedInnerRectClipper(LayoutObject&, const PaintInfo&, const LayoutRect&, const FloatRoundedRect& clipRect, RoundedInnerRectClipperBehavior);
     ~RoundedInnerRectClipper();
 
+    void begin(const LayoutRect&, const FloatRoundedRect& clipRect, RoundedInnerRectClipperBehavior);
+
 private:
     LayoutObject& m_layoutObject;
     const PaintInfo& m_paintInfo;
+
+    // Valid only if |m_engaged| is true.
     bool m_useDisplayItemList;
     DisplayItem::Type m_clipType;
+
+    bool m_engaged;
 };
 
 } // namespace blink