Add gpu implementation of SkAvoidXfermode

include/client/android/SkAvoidXfermode.h

 /*
  * Copyright 2006 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 SkAvoidXfermode_DEFINED
 #define SkAvoidXfermode_DEFINED
 
@@ skipping 33 matching lines @@
     }
 
     // overrides from SkXfermode
     void xfer32(SkPMColor dst[], const SkPMColor src[], int count,
                 const SkAlpha aa[]) const override;
     void xfer16(uint16_t dst[], const SkPMColor src[], int count,
                 const SkAlpha aa[]) const override;
     void xferA8(SkAlpha dst[], const SkPMColor src[], int count,
                 const SkAlpha aa[]) const override;
 
+#if SK_SUPPORT_GPU
+    bool asFragmentProcessor(const GrFragmentProcessor** output,
+                             const GrFragmentProcessor* dst) const override;
+    bool asXPFactory(GrXPFactory** xpf) const override;
+#endif
+
     SK_TO_STRING_OVERRIDE()
     SK_DECLARE_PUBLIC_FLATTENABLE_DESERIALIZATION_PROCS(AvoidXfermode)
 
 protected:
     SkAvoidXfermode(SkColor opColor, U8CPU tolerance, Mode mode);
     void flatten(SkWriteBuffer&) const override;
 
 private:
     SkColor     fOpColor;
     uint32_t    fDistMul;   // x.14 cached from fTolerance
     uint8_t     fTolerance;
     Mode        fMode;
 
     typedef SkXfermode INHERITED;
 };
 
 #endif