Refactor to put SkXfermode_opts inside SK_OPTS_NS.

src/core/SkOpts.cpp

 /*
  * Copyright 2015 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkOnce.h"
 #include "SkOpts.h"
 
@@ skipping 19 matching lines @@
 #endif
 
 namespace SkOpts {
     // Define default function pointer values here...
     // If our global compile options are set high enough, these 'portable' defaults might
     // even be CPU-specialized, e.g. a typical x86-64 machine might start with SSE2 defaults.
     // They'll still get a chance to be replaced with even better ones, e.g. using SSE4.1.
     decltype(rsqrt)                     rsqrt = portable::rsqrt;
     decltype(memset16)               memset16 = portable::memset16;
     decltype(memset32)               memset32 = portable::memset32;
-    decltype(create_xfermode) create_xfermode = SkCreate4pxXfermode;
+    decltype(create_xfermode) create_xfermode = portable::create_xfermode;
 
     decltype(box_blur_xx) box_blur_xx = portable::box_blur_xx;
     decltype(box_blur_xy) box_blur_xy = portable::box_blur_xy;
     decltype(box_blur_yx) box_blur_yx = portable::box_blur_yx;
 
     decltype(dilate_x) dilate_x = portable::dilate_x;
     decltype(dilate_y) dilate_y = portable::dilate_y;
     decltype( erode_x)  erode_x = portable::erode_x;
     decltype( erode_y)  erode_y = portable::erode_y;
 
@@ skipping 26 matching lines @@
 
     SK_DECLARE_STATIC_ONCE(gInitOnce);
     void Init() { SkOnce(&gInitOnce, init); }
 
 #if SK_ALLOW_STATIC_GLOBAL_INITIALIZERS
     static struct AutoInit {
         AutoInit() { Init(); }
     } gAutoInit;
 #endif
 }