remove code from (dead) SK_SUPPORT_LEGACY_PIXELREF_UNFLATTENABLE flag

Source/platform/graphics/DiscardablePixelRef.h

 /*
  * Copyright (C) 2013 Google 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 35 matching lines @@
 
 // PixelRef object whose memory can be discarded when pixels are unlocked.
 class PLATFORM_EXPORT DiscardablePixelRef : public SkPixelRef {
 public:
     DiscardablePixelRef(const SkImageInfo&, size_t rowBytes, PassOwnPtr<SkMutex>);
     virtual ~DiscardablePixelRef();
 
     static bool isDiscardable(SkPixelRef*);
     bool allocAndLockDiscardableMemory(size_t);
 
-#ifdef SK_SUPPORT_LEGACY_PIXELREF_UNFLATTENABLE
-    SK_DECLARE_UNFLATTENABLE_OBJECT()
-#endif
-
 protected:
     // SkPixelRef implementation.
     virtual bool onNewLockPixels(LockRec*) OVERRIDE;
     virtual void onUnlockPixels() OVERRIDE;
 
 private:
     void* m_lockedMemory;
     OwnPtr<blink::WebDiscardableMemory> m_discardable;
     OwnPtr<SkMutex> m_mutex;
     size_t m_rowBytes;
 };
 
 } // namespace WebCore
 
 #endif