Port most uses of SkOnce to SkLazyPtr.

src/core/SkLazyPtr.h

 /*
  * Copyright 2014 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef SkLazyPtr_DEFINED
 #define SkLazyPtr_DEFINED
 
@@ skipping 46 matching lines @@
 
 
 // Everything below here is private implementation details.  Don't touch, don't even look.
 
 #include "SkDynamicAnnotations.h"
 #include "SkThread.h"
 #include "SkThreadPriv.h"
 
 // See FIXME below.
 class SkFontConfigInterface;
-class SkTypeface;
 
 namespace Private {
 
 template <typename T> void sk_delete(T* ptr) { SkDELETE(ptr); }
 
 // Set *dst to ptr if *dst is NULL.  Returns value of *dst, destroying ptr if not swapped in.
 // Issues the same memory barriers as sk_atomic_cas: acquire on failure, release on success.
 template <typename P, void (*Destroy)(P)>
 static P try_cas(void** dst, P ptr) {
     P prev = (P)sk_atomic_cas(dst, NULL, ptr);
@@ skipping 15 matching lines @@
     T* get() {
         // If fPtr has already been filled, we need an acquire barrier when loading it.
         // If not, we need a release barrier when setting it.  try_cas will do that.
         T* ptr = (T*)sk_acquire_load(&fPtr);
         return ptr ? ptr : try_cas<T*, Destroy>(&fPtr, Create());
     }
 
 #ifdef SK_DEVELOPER
     // FIXME: We know we leak refs on some classes.  For now, let them leak.
     void cleanup(SkFontConfigInterface*) {}
-    void cleanup(SkTypeface*) {}
     template <typename U> void cleanup(U* ptr) { Destroy(ptr); }
 
     ~SkLazyPtr() {
         this->cleanup((T*)fPtr);
         fPtr = NULL;
     }
 #endif
 
 private:
     void* fPtr;
@@ skipping 20 matching lines @@
     }
 #endif
 
 private:
     void* fArray[N];
 };
 
 }  // namespace Private
 
 #endif//SkLazyPtr_DEFINED