Make SkImageFilter methods const.

src/effects/SkBlurImageFilter.cpp

 /*
  * Copyright 2011 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.
  */
 
 #include "SkBitmap.h"
 #include "SkBlurImageFilter.h"
 #include "SkColorPriv.h"
@@ skipping 118 matching lines @@
         *kernelSize3 = d;
     } else {
         *highOffset = d / 2;
         *lowOffset = *highOffset - 1;
         *kernelSize3 = d + 1;
     }
 }
 
 bool SkBlurImageFilter::onFilterImage(Proxy* proxy,
                                       const SkBitmap& source, const SkMatrix& ctm,
-                                      SkBitmap* dst, SkIPoint* offset) {
+                                      SkBitmap* dst, SkIPoint* offset) const {
     SkBitmap src = source;
     SkIPoint srcOffset = SkIPoint::Make(0, 0);
     if (getInput(0) && !getInput(0)->filterImage(proxy, source, ctm, &src, &srcOffset)) {
         return false;
     }
 
     if (src.config() != SkBitmap::kARGB_8888_Config) {
         return false;
     }
 
@@ skipping 95 matching lines @@
     }
     SkVector sigma, localSigma = SkVector::Make(fSigma.width(), fSigma.height());
     ctm.mapVectors(&sigma, &localSigma, 1);
     bounds.outset(SkScalarCeilToInt(SkScalarMul(sigma.x(), SkIntToScalar(3))),
                   SkScalarCeilToInt(SkScalarMul(sigma.y(), SkIntToScalar(3))));
     *dst = bounds;
     return true;
 }
 
 bool SkBlurImageFilter::filterImageGPU(Proxy* proxy, const SkBitmap& src, const SkMatrix& ctm,
-                                       SkBitmap* result, SkIPoint* offset) {
+                                       SkBitmap* result, SkIPoint* offset) const {
 #if SK_SUPPORT_GPU
     SkBitmap input;
     SkIPoint srcOffset = SkIPoint::Make(0, 0);
     if (!SkImageFilterUtils::GetInputResultGPU(getInput(0), proxy, src, ctm, &input, &srcOffset)) {
         return false;
     }
     GrTexture* source = input.getTexture();
     SkIRect rect;
     src.getBounds(&rect);
     rect.offset(srcOffset);
@@ skipping 11 matching lines @@
                                                              SkRect::Make(rect),
                                                              true,
                                                              sigma.x(),
                                                              sigma.y()));
     return SkImageFilterUtils::WrapTexture(tex, rect.width(), rect.height(), result);
 #else
     SkDEBUGFAIL("Should not call in GPU-less build");
     return false;
 #endif
 }