Make SkImageFilter methods const.

include/effects/SkMatrixConvolutionImageFilter.h

 /*
  * Copyright 2012 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 SkMatrixConvolutionImageFilter_DEFINED
 #define SkMatrixConvolutionImageFilter_DEFINED
 
@@ skipping 50 matching lines @@
                                    const CropRect* cropRect = NULL);
     virtual ~SkMatrixConvolutionImageFilter();
 
     SK_DECLARE_PUBLIC_FLATTENABLE_DESERIALIZATION_PROCS(SkMatrixConvolutionImageFilter)
 
 protected:
     SkMatrixConvolutionImageFilter(SkReadBuffer& buffer);
     virtual void flatten(SkWriteBuffer&) const SK_OVERRIDE;
 
     virtual bool onFilterImage(Proxy*, const SkBitmap& src, const SkMatrix&,
-                               SkBitmap* result, SkIPoint* loc) SK_OVERRIDE;
+                               SkBitmap* result, SkIPoint* loc) const SK_OVERRIDE;
 
 #if SK_SUPPORT_GPU
     virtual bool asNewEffect(GrEffectRef** effect,
                              GrTexture*,
                              const SkMatrix& matrix,
                              const SkIRect& bounds) const SK_OVERRIDE;
 #endif
 
 private:
     SkISize   fKernelSize;
     SkScalar* fKernel;
     SkScalar  fGain;
     SkScalar  fBias;
     SkIPoint  fTarget;
     TileMode  fTileMode;
     bool      fConvolveAlpha;
     typedef SkImageFilter INHERITED;
 
     template <class PixelFetcher, bool convolveAlpha>
     void filterPixels(const SkBitmap& src,
                       SkBitmap* result,
                       const SkIRect& rect,
-                      const SkIRect& bounds);
+                      const SkIRect& bounds) const;
     template <class PixelFetcher>
     void filterPixels(const SkBitmap& src,
                       SkBitmap* result,
                       const SkIRect& rect,
-                      const SkIRect& bounds);
+                      const SkIRect& bounds) const;
     void filterInteriorPixels(const SkBitmap& src,
                               SkBitmap* result,
                               const SkIRect& rect,
-                              const SkIRect& bounds);
+                              const SkIRect& bounds) const;
     void filterBorderPixels(const SkBitmap& src,
                             SkBitmap* result,
                             const SkIRect& rect,
-                            const SkIRect& bounds);
+                            const SkIRect& bounds) const;
 };
 
 #endif