Make SkPictureShader and SkPictureImageFilter use const SkPictures

src/core/SkPictureShader.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 SkPictureShader_DEFINED
 #define SkPictureShader_DEFINED
 
 #include "SkShader.h"
 
 class SkBitmap;
 class SkPicture;
 
 /*
  * An SkPictureShader can be used to draw SkPicture-based patterns.
  *
  * The SkPicture is first rendered into a tile, which is then used to shade the area according
  * to specified tiling rules.
  */
 class SkPictureShader : public SkShader {
 public:
-    static SkPictureShader* Create(SkPicture*, TileMode, TileMode, const SkMatrix* = NULL);
+    static SkPictureShader* Create(const SkPicture*, TileMode, TileMode, const SkMatrix* = NULL);
     virtual ~SkPictureShader();
 
     virtual size_t contextSize() const SK_OVERRIDE;
 
     SK_TO_STRING_OVERRIDE()
     SK_DECLARE_PUBLIC_FLATTENABLE_DESERIALIZATION_PROCS(SkPictureShader)
 
     bool asNewEffect(GrContext*, const SkPaint&, const SkMatrix*, GrColor*, GrEffect**)
         const SK_OVERRIDE;
 
 protected:
     SkPictureShader(SkReadBuffer&);
     virtual void flatten(SkWriteBuffer&) const SK_OVERRIDE;
     virtual Context* onCreateContext(const ContextRec&, void* storage) const SK_OVERRIDE;
 
 private:
-    SkPictureShader(SkPicture*, TileMode, TileMode, const SkMatrix* = NULL);
+    SkPictureShader(const SkPicture*, TileMode, TileMode, const SkMatrix* = NULL);
 
     SkShader* refBitmapShader(const SkMatrix&, const SkMatrix* localMatrix) const;
 
-    SkPicture*  fPicture;
-    TileMode    fTmx, fTmy;
+    const SkPicture*  fPicture;
+    TileMode          fTmx, fTmy;
 
     mutable SkMutex                 fCachedBitmapShaderMutex;
     mutable SkAutoTUnref<SkShader>  fCachedBitmapShader;
     mutable SkSize                  fCachedTileScale;
 
     class PictureShaderContext : public SkShader::Context {
     public:
         static Context* Create(void* storage, const SkPictureShader&, const ContextRec&,
                                SkShader* bitmapShader);
 
@@ skipping 12 matching lines @@
         SkShader::Context*      fBitmapShaderContext;
         void*                   fBitmapShaderContextStorage;
 
         typedef SkShader::Context INHERITED;
     };
 
     typedef SkShader INHERITED;
 };
 
 #endif // SkPictureShader_DEFINED