Remove willReadDst from GrFragmentProcessor.

include/gpu/GrFragmentProcessor.h

 /*
  * Copyright 2014 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef GrFragmentProcessor_DEFINED
 #define GrFragmentProcessor_DEFINED
 
 #include "GrProcessor.h"
 
 class GrCoordTransform;
 class GrGLCaps;
 class GrGLFragmentProcessor;
 class GrProcessorKeyBuilder;
 
 /** Provides custom fragment shader code. Fragment processors receive an input color (vec4f) and
     produce an output color. They may reference textures and uniforms. They may use
     GrCoordTransforms to receive a transformation of the local coordinates that map from local space
     to the fragment being processed.
  */
 class GrFragmentProcessor : public GrProcessor {
 public:
     GrFragmentProcessor()
         : INHERITED()
-        , fWillReadDstColor(false)
         , fWillUseInputColor(true)
         , fUsesLocalCoords(false) {}
 
     /** Implemented using GLFragmentProcessor::GenKey as described in this class's comment. */
     virtual void getGLProcessorKey(const GrGLCaps& caps,
                                    GrProcessorKeyBuilder* b) const = 0;
 
     /** Returns a new instance of the appropriate *GL* implementation class
         for the given GrFragmentProcessor; caller is responsible for deleting
         the object. */
     virtual GrGLFragmentProcessor* createGLInstance() const = 0;
 
     /** Human-meaningful string to identify this GrFragmentProcessor; may be embedded
         in generated shader code. */
     virtual const char* name() const = 0;
 
     int numTransforms() const { return fCoordTransforms.count(); }
 
     /** Returns the coordinate transformation at index. index must be valid according to
         numTransforms(). */
     const GrCoordTransform& coordTransform(int index) const { return *fCoordTransforms[index]; }
 
     const SkTArray<const GrCoordTransform*, true>& coordTransforms() const {
         return fCoordTransforms;
     }
 
-    /** Will this prceossor read the destination pixel value? */
-    bool willReadDstColor() const { return fWillReadDstColor; }
-
     /** Will this prceossor read the source color value? */
     bool willUseInputColor() const { return fWillUseInputColor; }
 
     /** Do any of the coordtransforms for this processor require local coords? */
     bool usesLocalCoords() const { return fUsesLocalCoords; }
 
     /** Returns true if this and other processor conservatively draw identically. It can only return
         true when the two processor are of the same subclass (i.e. they return the same object from
         from getFactory()).
 
@@ skipping 32 matching lines @@
      * processor subclass manages the lifetime of the transformations (this function only stores a
      * pointer). The GrCoordTransform is typically a member field of the GrProcessor subclass. 
      *
      * A processor subclass that has multiple methods of construction should always add its coord
      * transforms in a consistent order. The non-virtual implementation of isEqual() automatically
      * compares transforms and will assume they line up across the two processor instances.
      */
     void addCoordTransform(const GrCoordTransform*);
 
     /**
-     * If the prceossor subclass will read the destination pixel value then it must call this
-     * function from its constructor. Otherwise, when its generated backend-specific prceossor class
-     * attempts to generate code that reads the destination pixel it will fail.
-     */
-    void setWillReadDstColor() { fWillReadDstColor = true; }
-
-    /**
      * If the prceossor will generate a result that does not depend on the input color value then it
      * must call this function from its constructor. Otherwise, when its generated backend-specific
      * code might fail during variable binding due to unused variables.
      */
     void setWillNotUseInputColor() { fWillUseInputColor = false; }
 
     /**
      * Subclass implements this to support getConstantColorComponents(...).
      */
     virtual void onComputeInvariantOutput(GrInvariantOutput* inout) const = 0;
 
 private:
     /**
      * Subclass implements this to support isEqual(). It will only be called if it is known that
      * the two processors are of the same subclass (i.e. they return the same object from
      * getFactory()). The processor subclass should not compare its coord transforms as that will
      * be performed automatically in the non-virtual isEqual().
      */
     virtual bool onIsEqual(const GrFragmentProcessor&) const = 0;
 
     bool hasSameTransforms(const GrFragmentProcessor&) const;
 
     SkSTArray<4, const GrCoordTransform*, true>  fCoordTransforms;
-    bool                                         fWillReadDstColor;
     bool                                         fWillUseInputColor;
     bool                                         fUsesLocalCoords;
 
     typedef GrProcessor INHERITED;
 };
 
 #endif