switch xfermodes over to sk_sp

src/utils/SkLua.cpp

 /*
  * Copyright 2013 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkLua.h"
 
 #if SK_SUPPORT_GPU
@@ skipping 1080 matching lines @@
     SkXfermode* xfermode = paint->getXfermode();
     if (xfermode) {
         push_ref(L, xfermode);
         return 1;
     }
     return 0;
 }
 
 static int lpaint_setXfermode(lua_State* L) {
     SkPaint* paint = get_obj<SkPaint>(L, 1);
-    paint->setXfermode(get_ref<SkXfermode>(L, 2));
+    paint->setXfermode(sk_ref_sp(get_ref<SkXfermode>(L, 2)));
     return 0;
 }
 
 static int lpaint_getColorFilter(lua_State* L) {
     const SkPaint* paint = get_obj<SkPaint>(L, 1);
     SkColorFilter* cf = paint->getColorFilter();
     if (cf) {
         push_ref(L, cf);
         return 1;
     }
@@ skipping 1024 matching lines @@
     REG_CLASS(L, SkTextBlob);
     REG_CLASS(L, SkTypeface);
     REG_CLASS(L, SkXfermode);
 }
 
 extern "C" int luaopen_skia(lua_State* L);
 extern "C" int luaopen_skia(lua_State* L) {
     SkLua::Load(L);
     return 0;
 }