Alter SkXfermode's asFragmentProcessor & asXPFactory contracts

include/client/android/SkPixelXorXfermode.h

 /*
  * Copyright 2007 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 SkPixelXorXfermode_DEFINED
 #define SkPixelXorXfermode_DEFINED
 
 #include "SkXfermode.h"
 
 /** SkPixelXorXfermode implements a simple pixel xor (op ^ src ^ dst).
     This transformation does not follow premultiplied conventions, therefore
     this proc *always* returns an opaque color (alpha == 255). Thus it is
     not really usefull for operating on blended colors.
 */
 class SK_API SkPixelXorXfermode : public SkXfermode {
 public:
     static SkXfermode* Create(SkColor opColor) {
         return new SkPixelXorXfermode(opColor);
     }
 
 #if SK_SUPPORT_GPU
-    bool asFragmentProcessor(const GrFragmentProcessor** output,
-                             const GrFragmentProcessor* dst) const override;
-
-    bool asXPFactory(GrXPFactory**) const override;
+    const GrFragmentProcessor* asFragmentProcessor(const GrFragmentProcessor* dst) const override;
+    GrXPFactory* asXPFactory() const override;
 #endif
 
     SK_TO_STRING_OVERRIDE()
     SK_DECLARE_PUBLIC_FLATTENABLE_DESERIALIZATION_PROCS(SkPixelXorXfermode)
 
 protected:
     void flatten(SkWriteBuffer&) const override;
     SkPMColor xferColor(SkPMColor src, SkPMColor dst) const override;
 
 private:
     explicit SkPixelXorXfermode(SkColor opColor) {
         fOpColor = SkPreMultiplyColor(opColor | 0xFF000000);
     }
 
     SkPMColor fOpColor;
 
     typedef SkXfermode INHERITED;
 };
 
 #endif