Make SkPictureShader and SkPictureImageFilter use const SkPictures

src/core/SkPictureShader.cpp

 /*
  * Copyright 2014 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkPictureShader.h"
 
 #include "SkBitmap.h"
 #include "SkBitmapProcShader.h"
 #include "SkCanvas.h"
 #include "SkMatrixUtils.h"
 #include "SkPicture.h"
 #include "SkReadBuffer.h"
 
 #if SK_SUPPORT_GPU
 #include "GrContext.h"
 #endif
 
-SkPictureShader::SkPictureShader(SkPicture* picture, TileMode tmx, TileMode tmy,
+SkPictureShader::SkPictureShader(const SkPicture* picture, TileMode tmx, TileMode tmy,
                                  const SkMatrix* localMatrix)
     : INHERITED(localMatrix)
     , fPicture(SkRef(picture))
     , fTmx(tmx)
     , fTmy(tmy) { }
 
 SkPictureShader::SkPictureShader(SkReadBuffer& buffer)
         : INHERITED(buffer) {
     fTmx = static_cast<SkShader::TileMode>(buffer.read32());
     fTmy = static_cast<SkShader::TileMode>(buffer.read32());
     fPicture = SkPicture::CreateFromBuffer(buffer);
 }
 
 SkPictureShader::~SkPictureShader() {
     fPicture->unref();
 }
 
-SkPictureShader* SkPictureShader::Create(SkPicture* picture, TileMode tmx, TileMode tmy,
+SkPictureShader* SkPictureShader::Create(const SkPicture* picture, TileMode tmx, TileMode tmy,
                                          const SkMatrix* localMatrix) {
     if (!picture || 0 == picture->width() || 0 == picture->height()) {
         return NULL;
     }
     return SkNEW_ARGS(SkPictureShader, (picture, tmx, tmy, localMatrix));
 }
 
 void SkPictureShader::flatten(SkWriteBuffer& buffer) const {
     this->INHERITED::flatten(buffer);
 
@@ skipping 145 matching lines @@
     return bitmapShader->asNewEffect(context, paint, NULL, paintColor, effect);
 }
 #else
 bool SkPictureShader::asNewEffect(GrContext* context, const SkPaint& paint,
                                   const SkMatrix* localMatrix, GrColor* paintColor,
                                   GrEffect** effect) const {
     SkDEBUGFAIL("Should not call in GPU-less build");
     return false;
 }
 #endif