Create helper functions to use in computeInvariantOutput calls

src/effects/SkPerlinNoiseShader.cpp

 /*
  * Copyright 2013 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkDither.h"
 #include "SkPerlinNoiseShader.h"
 #include "SkColorFilter.h"
@@ skipping 569 matching lines @@
                fNumOctaves == s.fNumOctaves &&
                fStitchTiles == s.fStitchTiles &&
                fCoordTransform.getMatrix() == s.fCoordTransform.getMatrix() &&
                fAlpha == s.fAlpha &&
                fPermutationsAccess.getTexture() == s.fPermutationsAccess.getTexture() &&
                fNoiseAccess.getTexture() == s.fNoiseAccess.getTexture() &&
                fPaintingData->fStitchDataInit == s.fPaintingData->fStitchDataInit;
     }
 
     void onComputeInvariantOutput(InvariantOutput* inout) const SK_OVERRIDE {
-        inout->fValidFlags = 0; // This is noise. Nothing is constant.
-        inout->fIsSingleComponent = false;
+        inout->setToUnknown();
     }
 
     GrPerlinNoiseEffect(SkPerlinNoiseShader::Type type,
                         int numOctaves, bool stitchTiles,
                         SkPerlinNoiseShader::PaintingData* paintingData,
                         GrTexture* permutationsTexture, GrTexture* noiseTexture,
                         const SkMatrix& matrix, uint8_t alpha)
       : fType(type)
       , fNumOctaves(numOctaves)
       , fStitchTiles(stitchTiles)
@@ skipping 452 matching lines @@
     str->append(" seed: ");
     str->appendScalar(fSeed);
     str->append(" stitch tiles: ");
     str->append(fStitchTiles ? "true " : "false ");
 
     this->INHERITED::toString(str);
 
     str->append(")");
 }
 #endif