Use an image generator to back SkPictureShader tiles.

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(const SkPicture*, TileMode, TileMode, const SkMatrix*,
                                    const SkRect*);
-    virtual ~SkPictureShader();
 
     size_t contextSize() const SK_OVERRIDE;
 
     SK_TO_STRING_OVERRIDE()
     SK_DECLARE_PUBLIC_FLATTENABLE_DESERIALIZATION_PROCS(SkPictureShader)
 
     bool asFragmentProcessor(GrContext*, const SkPaint&, const SkMatrix& viewM, const SkMatrix*,
                              GrColor*, GrFragmentProcessor**) const SK_OVERRIDE;
 
 protected:
     SkPictureShader(SkReadBuffer&);
     void flatten(SkWriteBuffer&) const SK_OVERRIDE;
     Context* onCreateContext(const ContextRec&, void* storage) const SK_OVERRIDE;
 
 private:
     SkPictureShader(const SkPicture*, TileMode, TileMode, const SkMatrix*, const SkRect*);
 
     SkShader* refBitmapShader(const SkMatrix&, const SkMatrix* localMatrix) const;
 
-    const SkPicture* fPicture;
-    SkRect           fTile;
-    TileMode         fTmx, fTmy;
+    SkAutoTUnref<const SkPicture> fPicture;
+    SkRect                        fTile;
+    TileMode                      fTmx, fTmy;
 
     class PictureShaderContext : public SkShader::Context {
     public:
         static Context* Create(void* storage, const SkPictureShader&, const ContextRec&,
                                SkShader* bitmapShader);
 
         virtual ~PictureShaderContext();
 
         uint32_t getFlags() const SK_OVERRIDE;
 
         ShadeProc asAShadeProc(void** ctx) SK_OVERRIDE;
         void shadeSpan(int x, int y, SkPMColor dstC[], int count) SK_OVERRIDE;
         void shadeSpan16(int x, int y, uint16_t dstC[], int count) SK_OVERRIDE;
 
     private:
         PictureShaderContext(const SkPictureShader&, const ContextRec&, SkShader* bitmapShader);
 
         SkAutoTUnref<SkShader>  fBitmapShader;
         SkShader::Context*      fBitmapShaderContext;
         void*                   fBitmapShaderContextStorage;
 
         typedef SkShader::Context INHERITED;
     };
 
     typedef SkShader INHERITED;
 };
 
 #endif // SkPictureShader_DEFINED