Replace fWillReadFragmentPosition with a bitfield

src/gpu/effects/GrDitherEffect.cpp

 /*
  * Copyright 2014 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "GrDitherEffect.h"
 #include "GrFragmentProcessor.h"
 #include "GrInvariantOutput.h"
 #include "SkRect.h"
 #include "glsl/GrGLSLFragmentProcessor.h"
 #include "glsl/GrGLSLFragmentShaderBuilder.h"
 
 //////////////////////////////////////////////////////////////////////////////
 
 class DitherEffect : public GrFragmentProcessor {
 public:
     static GrFragmentProcessor* Create() {
         return new DitherEffect;
     }
 
     virtual ~DitherEffect() {};
 
     const char* name() const override { return "Dither"; }
 
 private:
     DitherEffect() {
         this->initClassID<DitherEffect>();
-        this->setWillReadFragmentPosition();
+        this->enableBuiltInState(kFragmentPosition_BuiltInState);
     }
 
     GrGLSLFragmentProcessor* onCreateGLSLInstance() const override;
 
     void onGetGLSLProcessorKey(const GrGLSLCaps&, GrProcessorKeyBuilder*) const override;
 
     // All dither effects are equal
     bool onIsEqual(const GrFragmentProcessor&) const override { return true; }
 
     void onComputeInvariantOutput(GrInvariantOutput* inout) const override;
@@ skipping 48 matching lines @@
 void DitherEffect::onGetGLSLProcessorKey(const GrGLSLCaps& caps,
                                          GrProcessorKeyBuilder* b) const {
     GLDitherEffect::GenKey(*this, caps, b);
 }
 
 GrGLSLFragmentProcessor* DitherEffect::onCreateGLSLInstance() const  {
     return new GLDitherEffect;
 }
 
 GrFragmentProcessor* GrDitherEffect::Create() { return DitherEffect::Create(); }