Replace fWillReadFragmentPosition with a bitfield

src/gpu/GrXferProcessor.cpp

 /*
  * Copyright 2015 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "GrXferProcessor.h"
 #include "GrPipeline.h"
 #include "GrPipelineBuilder.h"
@@ skipping 10 matching lines @@
                                  bool willReadDstColor,
                                  bool hasMixedSamples)
     : fWillReadDstColor(willReadDstColor)
     , fDstReadUsesMixedSamples(willReadDstColor && hasMixedSamples)
     , fDstTextureOffset() {
     if (dstTexture && dstTexture->texture()) {
         SkASSERT(willReadDstColor);
         fDstTexture.reset(dstTexture->texture());
         fDstTextureOffset = dstTexture->offset();
         this->addTextureAccess(&fDstTexture);
-        this->setWillReadFragmentPosition();
+        this->enableBuiltInState(kFragmentPosition_BuiltInState);
     }
 }
 
 GrXferProcessor::OptFlags GrXferProcessor::getOptimizations(
                                                        const GrPipelineOptimizations& optimizations,
                                                        bool doesStencilWrite,
                                                        GrColor* overrideColor,
                                                        const GrCaps& caps) const {
     GrXferProcessor::OptFlags flags = this->onGetOptimizations(optimizations,
                                                                doesStencilWrite,
@@ skipping 175 matching lines @@
     return (this->willReadDstColor(caps, optimizations, hasMixedSamples) &&
             !caps.shaderCaps()->dstReadInShaderSupport());
 }
 
 bool GrXPFactory::willReadDstColor(const GrCaps& caps,
                                    const GrPipelineOptimizations& optimizations,
                                    bool hasMixedSamples) const {
     return optimizations.fOverrides.fUsePLSDstRead || this->onWillReadDstColor(caps, optimizations,
                                                                                hasMixedSamples);
 }