Revert of Spin off just SkLazyFnPtr from 305513002.

src/core/SkLazyFnPtr.h

-#ifndef SkLazyFnPtr_DEFINED
-#define SkLazyFnPtr_DEFINED
-
-/** Declare a lazily-chosen static function pointer of type F.
- *
- *  Example usage:
- *
- *  typedef int (*FooImpl)(int, int);
- *
- *  static FooImpl choose_foo() { return ... };
- *
- *  int Foo(int a, int b) {
- *     SK_DECLARE_STATIC_LAZY_FN_PTR(FooImpl, choice);
- *     return choice.get(choose_foo)(a, b);
- *  }
- *
- *  You can think of SK_DECLARE_STATIC_LAZY_FN_PTR as a cheaper specialization of SkOnce.
- *  There is no mutex, and in the fast path, no memory barriers are issued.
- *
- *  This must be used in a global or function scope, not as a class member.
- */
-#define SK_DECLARE_STATIC_LAZY_FN_PTR(F, name) static Private::SkLazyFnPtr<F> name = { NULL }
-
-
-// Everything below here is private implementation details.  Don't touch, don't even look.
-
-#include "SkDynamicAnnotations.h"
-#include "SkThread.h"
-
-namespace Private {
-
-// This has no constructor and is link-time initialized, so its members must be public.
-template <typename F>
-struct SkLazyFnPtr {
-    F get(F (*choose)()) {
-        // First, try reading to see if it's already set.
-        F fn = (F)SK_ANNOTATE_UNPROTECTED_READ(fPtr);
-        if (fn != NULL) {
-            return fn;
-        }
-
-        // We think it's not already set.
-        fn = choose();
-
-        // No particular memory barriers needed; we're not guarding anything but the pointer itself.
-        F prev = (F)sk_atomic_cas(&fPtr, NULL, (void*)fn);
-
-        // If prev != NULL, someone snuck in and set fPtr concurrently.
-        // If prev == NULL, we did write fn to fPtr.
-        return prev != NULL ? prev : fn;
-    }
-
-    void* fPtr;
-};
-
-}  // namespace Private
-
-#endif//SkLazyFnPtr_DEFINED