Make SkImageFilter::asNewEffect() (and all derived-class overrides) protected.

include/effects/SkMagnifierImageFilter.h

Index: include/effects/SkMagnifierImageFilter.h
diff --git a/include/effects/SkMagnifierImageFilter.h b/include/effects/SkMagnifierImageFilter.h
index 31b446f6a5c53721a1b4e8b92d64201249aeb331..9ce349d11eaea0a7f068055b7b1fe171039a0676 100644
--- a/include/effects/SkMagnifierImageFilter.h
+++ b/include/effects/SkMagnifierImageFilter.h
@@ -16,10 +16,6 @@ class SK_API SkMagnifierImageFilter : public SkImageFilter {
 public:
     SkMagnifierImageFilter(SkRect srcRect, SkScalar inset);
 
-#if SK_SUPPORT_GPU
-    virtual bool asNewEffect(GrEffectRef** effect, GrTexture* texture, const SkMatrix& matrix) const SK_OVERRIDE;
-#endif
-
     SK_DECLARE_PUBLIC_FLATTENABLE_DESERIALIZATION_PROCS(SkMagnifierImageFilter)
 
 protected:
@@ -28,6 +24,9 @@ protected:
 
     virtual bool onFilterImage(Proxy*, const SkBitmap& src, const SkMatrix&,
                                SkBitmap* result, SkIPoint* offset) SK_OVERRIDE;
+#if SK_SUPPORT_GPU
+    virtual bool asNewEffect(GrEffectRef** effect, GrTexture* texture, const SkMatrix& matrix) const SK_OVERRIDE;
+#endif
 
 private:
     SkRect fSrcRect;