Bug 1441059 - Add cycle collection implementations for Maybe. r=bz

mfbt/Maybe.h

@@ -22,6 +22,8 @@
 #include <ostream>
 #include <type_traits>
 
+class nsCycleCollectionTraversalCallback;
+
 namespace mozilla {
 
 struct Nothing { };
@@ -713,6 +715,28 @@ operator>=(const Maybe<T>& aLHS, const Maybe<T>& aRHS)
   return !(aLHS < aRHS);
 }
 
+
+template<typename T>
+void
+ImplCycleCollectionTraverse(nsCycleCollectionTraversalCallback& aCallback,
+                            Maybe<T>& aMaybe,
+                            const char* aName,
+                            uint32_t aFlags = 0)
+{
+  if (aMaybe.isSome()) {
+    ImplCycleCollectionTraverse(aCallback, aMaybe.ref(), aName, aFlags);
+  }
+}
+
+template<typename T>
+void
+ImplCycleCollectionUnlink(Maybe<T>& aMaybe)
+{
+  if (aMaybe.isSome()) {
+    ImplCycleCollectionUnlink(aMaybe.ref());
+  }
+}
+
 } // namespace mozilla
 
 #endif /* mozilla_Maybe_h */