Make SkImageFilter methods const.

src/gpu/SkGpuDevice.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 "SkGpuDevice.h"
 
 #include "effects/GrBicubicEffect.h"
@@ skipping 1497 matching lines @@
     grPaint.addColorEffect(effect);
     bool alphaOnly = !(SkBitmap::kA8_Config == bitmap.config());
     if (!skPaint2GrPaintNoShader(this, paint, alphaOnly, false, &grPaint)) {
         return;
     }
 
     fContext->drawRectToRect(grPaint, dstRect, paintRect, NULL);
 }
 
 static bool filter_texture(SkBaseDevice* device, GrContext* context,
-                           GrTexture* texture, SkImageFilter* filter,
+                           GrTexture* texture, const SkImageFilter* filter,
                            int w, int h, const SkMatrix& ctm, SkBitmap* result,
                            SkIPoint* offset) {
     SkASSERT(filter);
     SkDeviceImageFilterProxy proxy(device);
 
     if (filter->canFilterImageGPU()) {
         // Save the render target and set it to NULL, so we don't accidentally draw to it in the
         // filter.  Also set the clip wide open and the matrix to identity.
         GrContext::AutoWideOpenIdentityDraw awo(context, NULL);
         return filter->filterImageGPU(&proxy, wrap_texture(texture), ctm, result, offset);
@@ skipping 158 matching lines @@
                                       SkIntToScalar(h));
 
     // The device being drawn may not fill up its texture (e.g. saveLayer uses approximate
     // scratch texture).
     SkRect srcRect = SkRect::MakeWH(SK_Scalar1 * w / devTex->width(),
                                     SK_Scalar1 * h / devTex->height());
 
     fContext->drawRectToRect(grPaint, dstRect, srcRect);
 }
 
-bool SkGpuDevice::canHandleImageFilter(SkImageFilter* filter) {
+bool SkGpuDevice::canHandleImageFilter(const SkImageFilter* filter) {
     return filter->canFilterImageGPU();
 }
 
-bool SkGpuDevice::filterImage(SkImageFilter* filter, const SkBitmap& src,
+bool SkGpuDevice::filterImage(const SkImageFilter* filter, const SkBitmap& src,
                               const SkMatrix& ctm,
                               SkBitmap* result, SkIPoint* offset) {
     // want explicitly our impl, so guard against a subclass of us overriding it
     if (!this->SkGpuDevice::canHandleImageFilter(filter)) {
         return false;
     }
 
     SkAutoLockPixels alp(src, !src.getTexture());
     if (!src.getTexture() && !src.readyToDraw()) {
         return false;
@@ skipping 210 matching lines @@
                          GrTexture* texture,
                          bool needClear)
     : SkBitmapDevice(make_bitmap(context, texture->asRenderTarget())) {
 
     SkASSERT(texture && texture->asRenderTarget());
     // This constructor is called from onCreateCompatibleDevice. It has locked the RT in the texture
     // cache. We pass true for the third argument so that it will get unlocked.
     this->initFromRenderTarget(context, texture->asRenderTarget(), true);
     fNeedClear = needClear;
 }