Remove SkShader virtual method validContext

include/effects/SkTransparentShader.h

 /*
  * Copyright 2006 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.
  */
 
 #ifndef SkTransparentShader_DEFINED
 #define SkTransparentShader_DEFINED
 
 #include "SkShader.h"
 
 class SK_API SkTransparentShader : public SkShader {
 public:
     SkTransparentShader() {}
 
-    virtual SkShader::Context* createContext(const ContextRec&, void* storage) const
-            SK_OVERRIDE;
     virtual size_t contextSize() const SK_OVERRIDE;
 
     class TransparentShaderContext : public SkShader::Context {
     public:
         TransparentShaderContext(const SkTransparentShader& shader, const ContextRec&);
         virtual ~TransparentShaderContext();
 
         virtual uint32_t getFlags() const SK_OVERRIDE;
         virtual void shadeSpan(int x, int y, SkPMColor[], int count) SK_OVERRIDE;
         virtual void shadeSpan16(int x, int y, uint16_t span[], int count) SK_OVERRIDE;
 
     private:
         const SkBitmap* fDevice;
 
         typedef SkShader::Context INHERITED;
     };
 
     SK_TO_STRING_OVERRIDE()
     SK_DECLARE_PUBLIC_FLATTENABLE_DESERIALIZATION_PROCS(SkTransparentShader)
 
+protected:
+    virtual Context* onCreateContext(const ContextRec&, void* storage) const SK_OVERRIDE;
+
 private:
     SkTransparentShader(SkReadBuffer& buffer) : INHERITED(buffer) {}
 
     typedef SkShader INHERITED;
 };
 
 #endif