create struct to hold all the params passed around for shader::context

include/effects/SkPerlinNoiseShader.h

 /*
  * Copyright 2013 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef SkPerlinNoiseShader_DEFINED
 #define SkPerlinNoiseShader_DEFINED
 
@@ skipping 54 matching lines @@
      * Create alias for CreateTurbulunce until all Skia users changed
      * its code to use the new naming
      */
     static SkShader* CreateTubulence(SkScalar baseFrequencyX, SkScalar baseFrequencyY,
                                      int numOctaves, SkScalar seed,
                                      const SkISize* tileSize = NULL) {
     return CreateTurbulence(baseFrequencyX, baseFrequencyY, numOctaves, seed, tileSize);
     }
 
 
-    virtual SkShader::Context* createContext(
-        const SkBitmap& device, const SkPaint& paint,
-        const SkMatrix& matrix, void* storage) const SK_OVERRIDE;
+    virtual SkShader::Context* createContext(const ContextRec&, void* storage) const SK_OVERRIDE;
     virtual size_t contextSize() const SK_OVERRIDE;
 
     class PerlinNoiseShaderContext : public SkShader::Context {
     public:
-        PerlinNoiseShaderContext(const SkPerlinNoiseShader& shader, const SkBitmap& device,
-                                 const SkPaint& paint, const SkMatrix& matrix);
+        PerlinNoiseShaderContext(const SkPerlinNoiseShader& shader, const ContextRec&);
         virtual ~PerlinNoiseShaderContext() {}
 
         virtual void shadeSpan(int x, int y, SkPMColor[], int count) SK_OVERRIDE;
         virtual void shadeSpan16(int x, int y, uint16_t[], int count) SK_OVERRIDE;
 
     private:
         SkPMColor shade(const SkPoint& point, StitchData& stitchData) const;
         SkScalar calculateTurbulenceValueForPoint(
             int channel, const PaintingData& paintingData,
             StitchData& stitchData, const SkPoint& point) const;
@@ skipping 30 matching lines @@
     /*const*/ SkScalar                  fSeed;
     /*const*/ SkISize                   fTileSize;
     /*const*/ bool                      fStitchTiles;
 
     PaintingData* fPaintingData;
 
     typedef SkShader INHERITED;
 };
 
 #endif