Reland of SkOncePtr -> SkOnce

src/core/SkData.cpp

 /*
  * Copyright 2011 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkData.h"
 #include "SkOSFile.h"
-#include "SkOncePtr.h"
+#include "SkOnce.h"
 #include "SkReadBuffer.h"
 #include "SkStream.h"
 #include "SkWriteBuffer.h"
 
 SkData::SkData(const void* ptr, size_t size, ReleaseProc proc, void* context) {
     fPtr = const_cast<void*>(ptr);
     fSize = size;
     fReleaseProc = proc;
     fReleaseProcContext = context;
 }
@@ skipping 52 matching lines @@
     char* storage = (char*)sk_malloc_throw(actualLength);
     SkData* data = new (storage) SkData(length);
     if (srcOrNull) {
         memcpy(data->writable_data(), srcOrNull, length);
     }
     return sk_sp<SkData>(data);
 }
 
 ///////////////////////////////////////////////////////////////////////////////
 
-SK_DECLARE_STATIC_ONCE_PTR(SkData, gEmpty);
 sk_sp<SkData> SkData::MakeEmpty() {
-    SkData* data = SkRef(gEmpty.get([]{return new SkData(nullptr, 0, nullptr, nullptr); }));
-    return sk_sp<SkData>(data);
+    static SkOnce once;
+    static SkData* empty;
+
+    once([]{ empty = new SkData(nullptr, 0, nullptr, nullptr); });
+    return sk_ref_sp(empty);
 }
 
 // assumes fPtr was allocated via sk_malloc
 static void sk_free_releaseproc(const void* ptr, void*) {
     sk_free((void*)ptr);
 }
 
 sk_sp<SkData> SkData::MakeFromMalloc(const void* data, size_t length) {
     return sk_sp<SkData>(new SkData(data, length, sk_free_releaseproc, nullptr));
 }
@@ skipping 88 matching lines @@
 
 ///////////////////////////////////////////////////////////////////////////////
 
 sk_sp<SkData> SkData::MakeFromStream(SkStream* stream, size_t size) {
     sk_sp<SkData> data(SkData::MakeUninitialized(size));
     if (stream->read(data->writable_data(), size) != size) {
         return nullptr;
     }
     return data;
 }