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

src/effects/gradients/SkTwoPointConicalGradient.cpp

Index: src/effects/gradients/SkTwoPointConicalGradient.cpp
diff --git a/src/effects/gradients/SkTwoPointConicalGradient.cpp b/src/effects/gradients/SkTwoPointConicalGradient.cpp
index 6a503d2fb7bea439af3876228ca07a8cf79e7b4d..2b38363889141a9d92e580e52fbcfb8bb82700ed 100644
--- a/src/effects/gradients/SkTwoPointConicalGradient.cpp
+++ b/src/effects/gradients/SkTwoPointConicalGradient.cpp
@@ -115,6 +115,7 @@ SkFixed TwoPtRadial::nextT() {
 typedef void (*TwoPointConicalProc)(TwoPtRadial* rec, SkPMColor* dstC,
                                     const SkPMColor* cache, int toggle, int count);
 
+#if 0
 static void twopoint_clamp(TwoPtRadial* rec, SkPMColor* SK_RESTRICT dstC,
                            const SkPMColor* SK_RESTRICT cache, int toggle,
                            int count) {
@@ -165,6 +166,7 @@ static void twopoint_mirror(TwoPtRadial* rec, SkPMColor* SK_RESTRICT dstC,
         toggle = next_dither_toggle(toggle);
     }
 }
+#endif
 
 void SkTwoPointConicalGradient::init() {
     fRec.init(fCenter1, fRadius1, fCenter2, fRadius2);
@@ -194,6 +196,7 @@ bool SkTwoPointConicalGradient::isOpaque() const {
     return false;
 }
 
+#if 0
 void SkTwoPointConicalGradient::shadeSpan(int x, int y, SkPMColor* dstCParam,
                                           int count) {
     int toggle = init_dither_toggle(x, y);
@@ -267,6 +270,7 @@ bool SkTwoPointConicalGradient::setContext(const SkBitmap& device,
 
     return true;
 }
+#endif
 
 SkShader::BitmapType SkTwoPointConicalGradient::asABitmap(
     SkBitmap* bitmap, SkMatrix* matrix, SkShader::TileMode* xy) const {