Bug 1277260, part 1 - Make PtrInfo into a class and mark it final. r=smaug

MozReview-Commit-ID: 3UJ89eCkBsd

--HG--
extra : rebase_source : 90cecf5db10f391e6d7eec2bb1d44810fe5fdd3f

xpcom/base/nsCycleCollector.cpp

@@ -374,7 +374,7 @@ public:
 // Base types
 ////////////////////////////////////////////////////////////////////////
 
-struct PtrInfo;
+class PtrInfo;
 
 class EdgePool
 {
@@ -579,13 +579,15 @@ enum NodeColor { black, white, grey };
 // hundreds of thousands of them to be allocated and touched
 // repeatedly during each cycle collection.
 
-struct PtrInfo
+class PtrInfo final
 {
+public:
   void* mPointer;
   nsCycleCollectionParticipant* mParticipant;
   uint32_t mColor : 2;
   uint32_t mInternalRefs : 30;
   uint32_t mRefCount;
+
 private:
   EdgePool::Iterator mFirstChild;