Allow single-pass filters (which use asNewEffect()) to participate in the image filter DAG. This w…

include/effects/SkMagnifierImageFilter.h

 /*
  * Copyright 2012 The Android Open Source Project
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 
 #ifndef SkMagnifierImageFilter_DEFINED
 #define SkMagnifierImageFilter_DEFINED
 
 #include "SkRect.h"
 #include "SkImageFilter.h"
 
 class SK_API SkMagnifierImageFilter : public SkImageFilter {
 public:
     SkMagnifierImageFilter(SkRect srcRect, SkScalar inset);
 
-    virtual bool asNewEffect(GrEffectRef** effect, GrTexture* texture) const SK_OVERRIDE;
+#if SK_SUPPORT_GPU
+    virtual bool canFilterImageGPU() const { return true; }
+    virtual GrEffectRef* asNewEffect(GrTexture* texture) const SK_OVERRIDE;
+#endif
 
     SK_DECLARE_PUBLIC_FLATTENABLE_DESERIALIZATION_PROCS(SkMagnifierImageFilter)
 
 protected:
     explicit SkMagnifierImageFilter(SkFlattenableReadBuffer& buffer);
     virtual void flatten(SkFlattenableWriteBuffer&) const SK_OVERRIDE;
 
     virtual bool onFilterImage(Proxy*, const SkBitmap& src, const SkMatrix&,
                                SkBitmap* result, SkIPoint* offset) SK_OVERRIDE;
 
 private:
     SkRect fSrcRect;
     SkScalar fInset;
     typedef SkImageFilter INHERITED;
 };
 
 #endif