Make SkImage::readYUV8Planes const

include/core/SkImage.h

 /*
  * Copyright 2012 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef SkImage_DEFINED
 #define SkImage_DEFINED
 
@@ skipping 141 matching lines @@
     SkISize dimensions() const { return SkISize::Make(fWidth, fHeight); }
     SkIRect bounds() const { return SkIRect::MakeWH(fWidth, fHeight); }
     uint32_t uniqueID() const { return fUniqueID; }
     virtual bool isOpaque() const { return false; }
 
     /**
      * Extracts YUV planes from the SkImage and stores them in client-provided memory. The sizes
      * planes and rowBytes arrays are ordered [y, u, v].
      */
     bool readYUV8Planes(const SkISize[3], void* const planes[3], const size_t rowBytes[3],
-                        SkYUVColorSpace);
+                        SkYUVColorSpace) const;
 
     virtual SkShader* newShader(SkShader::TileMode,
                                 SkShader::TileMode,
                                 const SkMatrix* localMatrix = NULL) const;
 
     /**
      *  If the image has direct access to its pixels (i.e. they are in local
      *  RAM) return the (const) address of those pixels, and if not null, return
      *  the ImageInfo and rowBytes. The returned address is only valid while
      *  the image object is in scope.
@@ skipping 170 matching lines @@
 
 private:
     const int       fWidth;
     const int       fHeight;
     const uint32_t  fUniqueID;
 
     typedef SkRefCnt INHERITED;
 };
 
 #endif