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

Source/core/paint/ScopeRecorder.h

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef ScopeRecorder_h
 #define ScopeRecorder_h
 
 #include "wtf/PassOwnPtr.h"
 
 namespace blink {
 
 class DisplayItemList;
 class GraphicsContext;
 class LayoutObject;
 
 class ScopeRecorder {
 public:
-    ScopeRecorder(GraphicsContext&, const LayoutObject&);
+    enum ShouldBegin { BeginOnConstruction, DeferBegin };
+    ScopeRecorder(GraphicsContext&, const LayoutObject&, ShouldBegin = BeginOnConstruction);
     ~ScopeRecorder();
 
+    void begin();
+
 private:
     DisplayItemList* m_displayItemList;
     const LayoutObject& m_object;
+    bool m_engaged;
 };
 
 } // namespace blink
 
 #endif // ScopeRecorder_h