Add SkCachedData and use it for SkMipMap

src/core/SkBitmapProcState.h

 /*
  * Copyright 2007 The Android Open Source Project
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef SkBitmapProcState_DEFINED
 #define SkBitmapProcState_DEFINED
 
@@ skipping 122 matching lines @@
     ShaderProc32        fShaderProc32;      // chooseProcs
     ShaderProc16        fShaderProc16;      // chooseProcs
     // These are used if the shaderproc is NULL
     MatrixProc          fMatrixProc;        // chooseProcs
     SampleProc32        fSampleProc32;      // chooseProcs
     SampleProc16        fSampleProc16;      // chooseProcs
 
     SkBitmap            fOrigBitmap;        // CONSTRUCTOR
     SkBitmap            fScaledBitmap;      // chooseProcs
 
-    SkAutoTUnref<const SkMipMap> fCurrMip;
+    SkAutoTUnref<SkMipMap> fCurrMip;
     bool                fAdjustedMatrix;    // set by possiblyScaleImage
 
     MatrixProc chooseMatrixProc(bool trivial_matrix);
     bool chooseProcs(const SkMatrix& inv, const SkPaint&);
     ShaderProc32 chooseShaderProc32();
 
     // returns false if we did not try to scale the image. In that case, we
     // will need to "lock" its pixels some other way.
     bool possiblyScaleImage();
 
@@ skipping 61 matching lines @@
 void S32_D16_filter_DX(const SkBitmapProcState& s,
                        const uint32_t* xy, int count, uint16_t* colors);
 
 void highQualityFilter32(const SkBitmapProcState &s, int x, int y,
                          SkPMColor *SK_RESTRICT colors, int count);
 void highQualityFilter16(const SkBitmapProcState &s, int x, int y,
                          uint16_t *SK_RESTRICT colors, int count);
 
 
 #endif