Fix UB function problems for shaders and mask.

include/core/SkShader.h

 /*
  * Copyright 2006 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 SkShader_DEFINED
 #define SkShader_DEFINED
 
@@ skipping 131 matching lines @@
          */
         virtual uint8_t getSpan16Alpha() const { return fPaintAlpha; }
 
         /**
          *  Called for each span of the object being drawn. Your subclass should
          *  set the appropriate colors (with premultiplied alpha) that correspond
          *  to the specified device coordinates.
          */
         virtual void shadeSpan(int x, int y, SkPMColor[], int count) = 0;
 
-        typedef void (*ShadeProc)(void* ctx, int x, int y, SkPMColor[], int count);
+        typedef void (*ShadeProc)(const void* ctx, int x, int y, SkPMColor[], int count);

[reed1, 2015/12/17 18:12:14]

Its seems odd to me that this is declared const, since the logical equivalent is
to just call shadeSpan(), which is not const.

Can the caller in BitmapProc just not make its local variable const?

[herb_g, 2015/12/17 19:59:22]

Added comment as per our discussion.

         virtual ShadeProc asAShadeProc(void** ctx);
 
         /**
          *  Called only for 16bit devices when getFlags() returns
          *  kOpaqueAlphaFlag | kHasSpan16_Flag
          */
         virtual void shadeSpan16(int x, int y, uint16_t[], int count);
 
         /**
          *  Similar to shadeSpan, but only returns the alpha-channel for a span.
@@ skipping 276 matching lines @@
     SkMatrix fLocalMatrix;
 
     // So the SkLocalMatrixShader can whack fLocalMatrix in its SkReadBuffer constructor.
     friend class SkLocalMatrixShader;
     friend class SkBitmapProcShader;    // for computeTotalInverse()
 
     typedef SkFlattenable INHERITED;
 };
 
 #endif