[heap] Move ObjectStatsVisitor into the proper component.

src/heap/object-stats.h

 // Copyright 2015 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef V8_HEAP_OBJECT_STATS_H_
 #define V8_HEAP_OBJECT_STATS_H_
 
 #include "src/heap/heap.h"
 #include "src/objects.h"
 
@@ skipping 62 matching lines @@
  private:
   Heap* heap_;
 
   // Object counts and used memory by InstanceType
   size_t object_counts_[OBJECT_STATS_COUNT];
   size_t object_counts_last_time_[OBJECT_STATS_COUNT];
   size_t object_sizes_[OBJECT_STATS_COUNT];
   size_t object_sizes_last_time_[OBJECT_STATS_COUNT];
 };
 
+
+class ObjectStatsVisitor : public StaticMarkingVisitor<ObjectStatsVisitor> {
+ public:
+  static void Initialize(VisitorDispatchTable<Callback>* original);
+
+  static void VisitBase(VisitorId id, Map* map, HeapObject* obj);
+
+  static void CountFixedArray(FixedArrayBase* fixed_array,
+                              FixedArraySubInstanceType fast_type,
+                              FixedArraySubInstanceType dictionary_type);
+
+  template <VisitorId id>
+  static inline void Visit(Map* map, HeapObject* obj);
+};
+
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_HEAP_OBJECT_STATS_H_