Refactor to put SkXfermode_opts inside SK_OPTS_NS.

src/opts/SkXfermode_opts.h

Index: src/opts/SkXfermode_opts.h
diff --git a/src/opts/SkXfermode_opts.h b/src/opts/SkXfermode_opts.h
index e5ca257a2802fe55302fb8d6be01c9f76e7bf0d3..5394e636e76c1d93004672e996a8c829f849bd66 100644
--- a/src/opts/SkXfermode_opts.h
+++ b/src/opts/SkXfermode_opts.h
@@ -12,7 +12,7 @@
 #include "SkPMFloat.h"
 #include "SkXfermode_proccoeff.h"
 
-namespace /* TODO: SK_OPTS_NS */ {
+namespace SK_OPTS_NS {
 
 // Most xfermodes can be done most efficiently 4 pixels at a time in 8 or 16-bit fixed point.
 #define XFERMODE(Name) static Sk4px SK_VECTORCALL Name(Sk4px s, Sk4px d)
@@ -274,7 +274,7 @@ private:
     typedef SkProcCoeffXfermode INHERITED;
 };
 
-static SkXfermode* SkCreate4pxXfermode(const ProcCoeff& rec, SkXfermode::Mode mode) {
+static SkXfermode* create_xfermode(const ProcCoeff& rec, SkXfermode::Mode mode) {
     switch (mode) {
     #define CASE(Mode) case SkXfermode::k##Mode##_Mode: \
         return SkNEW_ARGS(Sk4pxXfermode, (rec, mode, &Mode, &xfer_aa<Mode>))