reorg global initialization, separating core from optional

include/core/SkFlattenable.h

Index: include/core/SkFlattenable.h
diff --git a/include/core/SkFlattenable.h b/include/core/SkFlattenable.h
index bccabc18fa86d9cdf22babca2ea2f280157d2f72..10cba1a2ec293916d16c711b757e726fe1dd63d0 100644
--- a/include/core/SkFlattenable.h
+++ b/include/core/SkFlattenable.h
@@ -49,7 +49,7 @@ class SkPrivateEffectInitializer;
 #define SK_DECLARE_PUBLIC_FLATTENABLE_DESERIALIZATION_PROCS(flattenable)    \
     private:                                                                \
     static SkFlattenable* CreateProc(SkReadBuffer&);                        \
-    friend class ::SkPrivateEffectInitializer;                              \
+    friend class SkFlattenable::PrivateInitializer;                         \
     public:                                                                 \
     Factory getFactory() const override { return CreateProc; }
 
@@ -108,6 +108,13 @@ public:
      */
     virtual void flatten(SkWriteBuffer&) const {}
 
+protected:
+    class PrivateInitializer {
+    public:
+        static void InitCore();
+        static void InitEffects();
+    };
+
 private:
     static void InitializeFlattenablesIfNeeded();