Revert of SkOncePtr -> SkOnce

src/core/SkXfermode.cpp

Index: src/core/SkXfermode.cpp
diff --git a/src/core/SkXfermode.cpp b/src/core/SkXfermode.cpp
index b6d23888a741d7611eb4c7a72c7937680b045d96..1cfe8647511088cea117a28b9438691e6abd4eb3 100644
--- a/src/core/SkXfermode.cpp
+++ b/src/core/SkXfermode.cpp
@@ -9,7 +9,7 @@
 #include "SkXfermode_proccoeff.h"
 #include "SkColorPriv.h"
 #include "SkMathPriv.h"
-#include "SkOnce.h"
+#include "SkOncePtr.h"
 #include "SkOpts.h"
 #include "SkReadBuffer.h"
 #include "SkString.h"
@@ -1303,7 +1303,11 @@
 #endif
 
 
+SK_DECLARE_STATIC_ONCE_PTR(SkXfermode, cached[SkXfermode::kLastMode + 1]);
+
 sk_sp<SkXfermode> SkXfermode::Make(Mode mode) {
+    SkASSERT(SK_ARRAY_COUNT(gProcCoeffs) == kModeCount);
+
     if ((unsigned)mode >= kModeCount) {
         // report error
         return nullptr;
@@ -1315,20 +1319,13 @@
         return nullptr;
     }
 
-    SkASSERT(SK_ARRAY_COUNT(gProcCoeffs) == kModeCount);
-
-    static SkOnce        once[SkXfermode::kLastMode+1];
-    static SkXfermode* cached[SkXfermode::kLastMode+1];
-
-    once[mode]([mode] {
+    return sk_ref_sp(cached[mode].get([=]{
         ProcCoeff rec = gProcCoeffs[mode];
         if (auto xfermode = SkOpts::create_xfermode(rec, mode)) {
-            cached[mode] = xfermode;
-        } else {
-            cached[mode] = new SkProcCoeffXfermode(rec, mode);
+            return xfermode;
         }
-    });
-    return sk_ref_sp(cached[mode]);
+        return (SkXfermode*) new SkProcCoeffXfermode(rec, mode);
+    }));
 }
 
 SkXfermodeProc SkXfermode::GetProc(Mode mode) {