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

Source/platform/graphics/paint/ClipRecorder.h

Index: Source/platform/graphics/paint/ClipRecorder.h
diff --git a/Source/platform/graphics/paint/ClipRecorder.h b/Source/platform/graphics/paint/ClipRecorder.h
index 5418754cfa8046d30723715edc68e1f56fdf0c29..4b9942403d8f15ee29847d3730a453b131f80188 100644
--- a/Source/platform/graphics/paint/ClipRecorder.h
+++ b/Source/platform/graphics/paint/ClipRecorder.h
@@ -16,12 +16,16 @@ class GraphicsContext;
 class PLATFORM_EXPORT ClipRecorder {
     WTF_MAKE_FAST_ALLOCATED(ClipRecorder);
 public:
+    ClipRecorder(GraphicsContext&, const DisplayItemClientWrapper&, DisplayItem::Type);
     ClipRecorder(GraphicsContext&, const DisplayItemClientWrapper&, DisplayItem::Type, const LayoutRect& clipRect, SkRegion::Op = SkRegion::kIntersect_Op);
     ~ClipRecorder();
+
+    void begin(const LayoutRect& clipRect, SkRegion::Op = SkRegion::kIntersect_Op);
 private:
     DisplayItemClientWrapper m_client;
     GraphicsContext& m_context;
     DisplayItem::Type m_type;
+    bool m_engaged;
 };
 
 } // namespace blink