SkOnce: add option to call another cleanup function once at exit.

src/core/SkPathRef.cpp

 /*
  * Copyright 2013 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkBuffer.h"
 #include "SkOnce.h"
 #include "SkPath.h"
@@ skipping 10 matching lines @@
         SkPathRef* copy = SkNEW(SkPathRef);
         copy->copy(**pathRef, incReserveVerbs, incReservePoints);
         pathRef->reset(copy);
     }
     fPathRef = *pathRef;
     fPathRef->fGenerationID = 0;
     SkDEBUGCODE(sk_atomic_inc(&fPathRef->fEditorsAttached);)
 }
 
 //////////////////////////////////////////////////////////////////////////////
-void SkPathRef::CreateEmptyImpl(SkPathRef** empty) {
-    *empty = SkNEW(SkPathRef);
-    (*empty)->computeBounds();  // Preemptively avoid a race to clear fBoundsIsDirty.
+static SkPathRef* gEmptyPathRef = NULL;
+static void cleanup_gEmptyPathRef() { gEmptyPathRef->unref(); }
+
+void SkPathRef::CreateEmptyImpl(int) {
+    gEmptyPathRef = SkNEW(SkPathRef);
+    gEmptyPathRef->computeBounds();  // Preemptively avoid a race to clear fBoundsIsDirty.
 }
 
 SkPathRef* SkPathRef::CreateEmpty() {
-    static SkPathRef* gEmptyPathRef;
     SK_DECLARE_STATIC_ONCE(once);
-    SkOnce(&once, SkPathRef::CreateEmptyImpl, &gEmptyPathRef);
+    SkOnce(&once, SkPathRef::CreateEmptyImpl, 0, cleanup_gEmptyPathRef);
     return SkRef(gEmptyPathRef);
 }
 
 void SkPathRef::CreateTransformedCopy(SkAutoTUnref<SkPathRef>* dst,
                                       const SkPathRef& src,
                                       const SkMatrix& matrix) {
     SkDEBUGCODE(src.validate();)
     if (matrix.isIdentity()) {
         if (*dst != &src) {
             src.ref();
@@ skipping 431 matching lines @@
                 break;
             default:
                 SkDEBUGFAIL("Unknown Verb");
                 break;
         }
     }
     SkASSERT(mask == fSegmentMask);
 #endif // SK_DEBUG_PATH
 }
 #endif