Using override keyword in ObjectVisitor class hierarchy.

src/heap/scavenger.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_SCAVENGER_H_
 #define V8_HEAP_SCAVENGER_H_
 
 #include "src/heap/objects-visiting.h"
 
 namespace v8 {
@@ skipping 30 matching lines @@
   VisitorDispatchTable<ScavengingCallback> scavenging_visitors_table_;
 };
 
 
 // Helper class for turning the scavenger into an object visitor that is also
 // filtering out non-HeapObjects and objects which do not reside in new space.
 class ScavengeVisitor : public ObjectVisitor {
  public:
   explicit ScavengeVisitor(Heap* heap) : heap_(heap) {}
 
-  void VisitPointer(Object** p);
-  void VisitPointers(Object** start, Object** end);
+  void VisitPointer(Object** p) override;
+  void VisitPointers(Object** start, Object** end) override;
 
  private:
   inline void ScavengePointer(Object** p);
 
   Heap* heap_;
 };
 
 
 // Helper class for turning the scavenger into an object visitor that is also
 // filtering out non-HeapObjects and objects which do not reside in new space.
 class StaticScavengeVisitor
     : public StaticNewSpaceVisitor<StaticScavengeVisitor> {
  public:
   static inline void VisitPointer(Heap* heap, Object** p);
 };
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_HEAP_SCAVENGER_H_