Revert of SkOncePtr -> SkOnce (patchset #4 id:60001 of https://codereview.chromium.org/1953533002/ )

Reason for revert:
broken the Mac and Linux builders, e.g.:

https://build.chromium.org/p/chromium/builders/Mac/builds/15151
https://build.chromium.org/p/chromium/builders/Linux%20x64/builds/19052

Original issue's description:
> SkOncePtr -> SkOnce
>
> It's always nice to kill off a synchronization primitive.
> And while less terse, I think this new code reads more clearly.
>
> ... and, SkOncePtr's tests were the only thing now using sk_num_cores()
> outside of SkTaskGroup, so I've hidden it as static inside SkTaskGroup.cpp.
>
> BUG=skia:
> GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1953533002
> CQ_EXTRA_TRYBOTS=client.skia:Test-Ubuntu-GCC-GCE-CPU-AVX2-x86_64-Release-SKNX_NO_SIMD-Trybot
>
> Committed: https://skia.googlesource.com/skia/+/9bd3fc7fa9bb7cad050bd619aa93d4c48ebb5c02

TBR=herb@google.com,mtklein@chromium.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=skia:

Review-Url: https://codereview.chromium.org/1945293004

1 files changed, 8 insertions, 10 deletions

diff --git a/src/core/SkPathRef.cpp b/src/core/SkPathRef.cpp
index 2fc2de935c..b18055136f 100644
--- a/src/core/SkPathRef.cpp
+++ b/src/core/SkPathRef.cpp
@@ -6,7 +6,7 @@
  */
 
 #include "SkBuffer.h"
-#include "SkOnce.h"
+#include "SkOncePtr.h"
 #include "SkPath.h"
 #include "SkPathRef.h"
 #include <limits>
@@ -45,15 +45,13 @@ SkPathRef::~SkPathRef() {
     SkDEBUGCODE(fEditorsAttached = 0x7777777;)
 }
 
-static SkPathRef* gEmpty = nullptr;
-
+SK_DECLARE_STATIC_ONCE_PTR(SkPathRef, empty);
 SkPathRef* SkPathRef::CreateEmpty() {
-    static SkOnce once;
-    once([]{
-        gEmpty = new SkPathRef;
-        gEmpty->computeBounds();   // Avoids races later to be the first to do this.
-    });
-    return SkRef(gEmpty);
+    return SkRef(empty.get([]{
+        SkPathRef* pr = new SkPathRef;
+        pr->computeBounds();   // Avoids races later to be the first to do this.
+        return pr;
+    }));
 }
 
 void SkPathRef::CreateTransformedCopy(SkAutoTUnref<SkPathRef>* dst,
@@ -471,7 +469,7 @@ uint32_t SkPathRef::genID() const {
 }
 
 void SkPathRef::addGenIDChangeListener(GenIDChangeListener* listener) {
-    if (nullptr == listener || this == gEmpty) {
+    if (nullptr == listener || this == (SkPathRef*)empty) {
         delete listener;
         return;
     }