Modernize and trim down SkOnce.

src/fonts/SkFontMgr_indirect.cpp

Index: src/fonts/SkFontMgr_indirect.cpp
diff --git a/src/fonts/SkFontMgr_indirect.cpp b/src/fonts/SkFontMgr_indirect.cpp
index d3fae91808af8d9f6d1019c2ab3a6ba4017ac4de..01a24c5174a2e46479c78a9e9dfe591e1901f75f 100644
--- a/src/fonts/SkFontMgr_indirect.cpp
+++ b/src/fonts/SkFontMgr_indirect.cpp
@@ -65,12 +65,12 @@ void SkFontMgr_Indirect::set_up_family_names(const SkFontMgr_Indirect* self) {
 }
 
 int SkFontMgr_Indirect::onCountFamilies() const {
-    SkOnce(&fFamilyNamesInited, &fFamilyNamesMutex, SkFontMgr_Indirect::set_up_family_names, this);
+    fFamilyNamesInitOnce(SkFontMgr_Indirect::set_up_family_names, this);
     return fFamilyNames->count();
 }
 
 void SkFontMgr_Indirect::onGetFamilyName(int index, SkString* familyName) const {
-    SkOnce(&fFamilyNamesInited, &fFamilyNamesMutex, SkFontMgr_Indirect::set_up_family_names, this);
+    fFamilyNamesInitOnce(SkFontMgr_Indirect::set_up_family_names, this);
     if (index >= fFamilyNames->count()) {
         familyName->reset();
         return;