Revert of Remove GP from drawstate, revision of invariant output for GP

include/gpu/GrXferProcessor.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 GrXferProcessor_DEFINED
 #define GrXferProcessor_DEFINED
 
@@ skipping 116 matching lines @@
 protected:
     GrXferProcessor() : fWillReadDstColor(false) {}
 
     /**
      * 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; }
 
-    /**
-     * Subclass implements this to support getConstantColorComponents(...).
-     */
-    virtual void onComputeInvariantOutput(GrInvariantOutput* inout) const = 0;
-
 private:
     virtual bool onIsEqual(const GrXferProcessor&) const = 0;
 
     bool         fWillReadDstColor;
 
     typedef GrFragmentProcessor INHERITED;
 };
 
 GR_MAKE_BITFIELD_OPS(GrXferProcessor::OptFlags);
 
@@ skipping 96 matching lines @@
     enum {
         kIllegalXPFClassID = 0,
     };
     static int32_t gCurrXPFClassID;
 
     typedef GrProgramElement INHERITED;
 };
 
 #endif