Make SkImageFilter methods const.

gm/imagefiltersbase.cpp

 /*
  * Copyright 2011 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "gm.h"
 #include "SkCanvas.h"
 #include "SkColorFilter.h"
 #include "SkColorPriv.h"
 #include "SkShader.h"
 
 #include "SkBlurImageFilter.h"
 #include "SkColorFilterImageFilter.h"
 #include "SkDropShadowImageFilter.h"
 #include "SkTestImageFilters.h"
 
 class FailImageFilter : public SkImageFilter {
 public:
     FailImageFilter() : INHERITED(0) {}
 
     SK_DECLARE_PUBLIC_FLATTENABLE_DESERIALIZATION_PROCS(FailImageFilter)
 protected:
     virtual bool onFilterImage(Proxy*, const SkBitmap& src, const SkMatrix&,
-                               SkBitmap* result, SkIPoint* offset) {
+                               SkBitmap* result, SkIPoint* offset) const {
         return false;
     }
 
     FailImageFilter(SkReadBuffer& buffer)
       : INHERITED(1, buffer) {}
 
 private:
     typedef SkImageFilter INHERITED;
 };
 
 // register the filter with the flattenable registry
 static SkFlattenable::Registrar gFailImageFilterReg("FailImageFilter",
                                                     FailImageFilter::CreateProc,
                                                     FailImageFilter::GetFlattenableType());
 
 class IdentityImageFilter : public SkImageFilter {
 public:
     IdentityImageFilter() : INHERITED(0) {}
 
     SK_DECLARE_PUBLIC_FLATTENABLE_DESERIALIZATION_PROCS(IdentityImageFilter)
 protected:
     virtual bool onFilterImage(Proxy*, const SkBitmap& src, const SkMatrix&,
-                               SkBitmap* result, SkIPoint* offset) {
+                               SkBitmap* result, SkIPoint* offset) const {
         *result = src;
         return true;
     }
 
     IdentityImageFilter(SkReadBuffer& buffer)
       : INHERITED(1, buffer) {}
 
 private:
     typedef SkImageFilter INHERITED;
 };
@@ skipping 160 matching lines @@
     }
 
 private:
     typedef GM INHERITED;
 };
 
 ///////////////////////////////////////////////////////////////////////////////
 
 static skiagm::GM* MyFactory(void*) { return new ImageFiltersBaseGM; }
 static skiagm::GMRegistry reg(MyFactory);