Port most uses of SkOnce to SkLazyPtr.

src/core/SkFontHost.cpp

Index: src/core/SkFontHost.cpp
diff --git a/src/core/SkFontHost.cpp b/src/core/SkFontHost.cpp
index 9e7eeb182d1790ba9f362fd9c2bcbcdaf91f150a..a16a8c42e02956274090876e842f6a5c3c68e3a2 100644
--- a/src/core/SkFontHost.cpp
+++ b/src/core/SkFontHost.cpp
@@ -6,7 +6,7 @@
  */
 
 #include "SkFontLCDConfig.h"
-#include "SkOnce.h"
+#include "SkLazyPtr.h"
 
 static SkFontLCDConfig::LCDOrientation gLCDOrientation = SkFontLCDConfig::kHorizontal_LCDOrientation;
 static SkFontLCDConfig::LCDOrder gLCDOrder = SkFontLCDConfig::kRGB_LCDOrder;
@@ -198,19 +198,14 @@ SkTypeface* SkFontMgr::legacyCreateTypeface(const char familyName[],
     return this->onLegacyCreateTypeface(familyName, styleBits);
 }
 
-void set_up_default(SkFontMgr** singleton) {
-  *singleton = SkFontMgr::Factory();
-  // we never want to return NULL
-  if (NULL == *singleton) {
-      *singleton = SkNEW(SkEmptyFontMgr);
-  }
+SkFontMgr* SkFontMgr::CreateDefault() {
+    SkFontMgr* fm = SkFontMgr::Factory();
+    return fm ? fm : SkNEW(SkEmptyFontMgr);
 }
 
 SkFontMgr* SkFontMgr::RefDefault() {
-    static SkFontMgr* gFM = NULL;
-    SK_DECLARE_STATIC_ONCE(once);
-    SkOnce(&once, set_up_default, &gFM);
-    return SkRef(gFM);
+    SK_DECLARE_STATIC_LAZY_PTR(SkFontMgr, singleton, CreateDefault);
+    return SkRef(singleton.get());
 }
 
 //////////////////////////////////////////////////////////////////////////