remove SK_SUPPORT_LEGACY_PIXELREF_UNFLATTENABLE code

src/lazy/SkCachingPixelRef.h

Index: src/lazy/SkCachingPixelRef.h
diff --git a/src/lazy/SkCachingPixelRef.h b/src/lazy/SkCachingPixelRef.h
index 193fe454823d9051675ee3fca3a16f49d60f8ab7..1e87874f74dd5d2ec151cd24652d01ad6feadf40 100644
--- a/src/lazy/SkCachingPixelRef.h
+++ b/src/lazy/SkCachingPixelRef.h
@@ -49,15 +49,6 @@ protected:
         return fImageGenerator->refEncodedData();
     }
 
-#ifdef SK_SUPPORT_LEGACY_PIXELREF_UNFLATTENABLE
-    // No need to flatten this object. When flattening an SkBitmap,
-    // SkWriteBuffer will check the encoded data and write that
-    // instead.
-    // Future implementations of SkWriteBuffer will need to
-    // special case for onRefEncodedData as well.
-    SK_DECLARE_UNFLATTENABLE_OBJECT()
-#endif
-
 private:
     SkImageGenerator* const fImageGenerator;
     bool                    fErrorInDecoding;