Remove SkShader virtual method validContext

src/effects/SkPerlinNoiseShader.cpp

 /*
  * Copyright 2013 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkDither.h"
 #include "SkPerlinNoiseShader.h"
 #include "SkColorFilter.h"
@@ skipping 407 matching lines @@
 
     U8CPU rgba[4];
     for (int channel = 3; channel >= 0; --channel) {
         rgba[channel] = SkScalarFloorToInt(255 *
             calculateTurbulenceValueForPoint(channel, *perlinNoiseShader.fPaintingData,
                                              stitchData, newPoint));
     }
     return SkPreMultiplyARGB(rgba[3], rgba[0], rgba[1], rgba[2]);
 }
 
-SkShader::Context* SkPerlinNoiseShader::createContext(const ContextRec& rec, void* storage) const {
-    if (!this->validContext(rec)) {
-        return NULL;
-    }
-
+SkShader::Context* SkPerlinNoiseShader::onCreateContext(const ContextRec& rec,
+                                                        void* storage) const {
     return SkNEW_PLACEMENT_ARGS(storage, PerlinNoiseShaderContext, (*this, rec));
 }
 
 size_t SkPerlinNoiseShader::contextSize() const {
     return sizeof(PerlinNoiseShaderContext);
 }
 
 SkPerlinNoiseShader::PerlinNoiseShaderContext::PerlinNoiseShaderContext(
         const SkPerlinNoiseShader& shader, const ContextRec& rec)
     : INHERITED(shader, rec)
@@ skipping 920 matching lines @@
     str->append(" seed: ");
     str->appendScalar(fSeed);
     str->append(" stitch tiles: ");
     str->append(fStitchTiles ? "true " : "false ");
 
     this->INHERITED::toString(str);
 
     str->append(")");
 }
 #endif