Extract most of the mutable state of SkShader into a separate Context object.

src/effects/gradients/SkGradientShaderPriv.h

Index: src/effects/gradients/SkGradientShaderPriv.h
diff --git a/src/effects/gradients/SkGradientShaderPriv.h b/src/effects/gradients/SkGradientShaderPriv.h
index 184ef8e88375c6d8dad48dd71588cce1c9f22299..92d6f55f35b6dc2fa813616e16b92971927d1ce6 100644
--- a/src/effects/gradients/SkGradientShaderPriv.h
+++ b/src/effects/gradients/SkGradientShaderPriv.h
@@ -101,8 +101,15 @@ public:
     SkGradientShaderBase(const Descriptor& desc);
     virtual ~SkGradientShaderBase();
 
+#if 0
     virtual bool setContext(const SkBitmap&, const SkPaint&, const SkMatrix&) SK_OVERRIDE;
     virtual uint32_t getFlags() SK_OVERRIDE { return fFlags; }
+#endif
+    virtual SkShader::Context* createContext(
+            const SkBitmap&, const SkPaint&, const SkMatrix&, void*) const SK_OVERRIDE {
+        return NULL;
+    }
+    virtual size_t contextSize() const SK_OVERRIDE { return 0; }
     virtual bool isOpaque() const SK_OVERRIDE;
 
     void getGradientTableBitmap(SkBitmap*) const;