Add DataPersistent<> for copy-on-modify and use for StyleFilterData.

third_party/WebKit/Source/core/style/StyleFilterData.h

 /*
  * Copyright (C) 2011 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 10 matching lines @@
  * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
 #ifndef StyleFilterData_h
 #define StyleFilterData_h
 
 #include "platform/graphics/filters/FilterOperations.h"
 #include "platform/heap/Handle.h"
-#include "wtf/PassRefPtr.h"
-#include "wtf/RefCounted.h"
 
 namespace blink {
 
-// FIXME: Oilpan: resorting to RefCountedGarbageCollected<> here so as to support
-// DataRef<StyleFilterData> uses. Once/if DataRef<> is able to move away from
-// relying on RefPtr<>, switch to GarbageCollected<>.
-class StyleFilterData final : public RefCountedGarbageCollected<StyleFilterData> {
+class StyleFilterData final : public GarbageCollected<StyleFilterData> {
 public:
     static StyleFilterData* create()
     {
         return new StyleFilterData;
     }
 
     StyleFilterData* copy() const
     {
         return new StyleFilterData(*this);
     }
@@ skipping 11 matching lines @@
 
     FilterOperations m_operations;
 
 private:
     StyleFilterData();
     explicit StyleFilterData(const StyleFilterData&);
 };
 
 } // namespace blink
 
-
 #endif // StyleFilterData_h