Show names for the strong roots in heap snapshot.

src/profile-generator.h

 // Copyright 2011 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 879 matching lines @@
 
 
 class HeapObjectsSet {
  public:
   HeapObjectsSet();
   void Clear();
   bool Contains(Object* object);
   void Insert(Object* obj);
   const char* GetTag(Object* obj);
   void SetTag(Object* obj, const char* tag);
+  bool is_empty() const { return entries_.occupancy() == 0; }
 
  private:
   HashMap entries_;
 
   DISALLOW_COPY_AND_ASSIGN(HeapObjectsSet);
 };
 
 
 // An interface used to populate a snapshot with nodes and edges.
 class SnapshotFillerInterface {
@@ skipping 108 matching lines @@
                             int field_offset = -1);
   void SetPropertyShortcutReference(HeapObject* parent_obj,
                                     HeapEntry* parent,
                                     String* reference_name,
                                     Object* child);
   void SetUserGlobalReference(Object* window);
   void SetRootGcRootsReference();
   void SetGcRootsReference(VisitorSynchronization::SyncTag tag);
   void SetGcSubrootReference(
       VisitorSynchronization::SyncTag tag, bool is_weak, Object* child);
+  const char* GetStrongGcSubrootName(Object* object);
   void SetObjectName(HeapObject* object);
   void TagObject(Object* obj, const char* tag);
 
   HeapEntry* GetEntry(Object* obj);
 
   static inline HeapObject* GetNthGcSubrootObject(int delta);
   static inline int GetGcSubrootOrder(HeapObject* subroot);
 
   Heap* heap_;
   HeapSnapshot* snapshot_;
   HeapSnapshotsCollection* collection_;
   SnapshottingProgressReportingInterface* progress_;
   SnapshotFillerInterface* filler_;
   HeapObjectsSet objects_tags_;
+  HeapObjectsSet strong_gc_subroot_names_;
 
   static HeapObject* const kGcRootsObject;
   static HeapObject* const kFirstGcSubrootObject;
   static HeapObject* const kLastGcSubrootObject;
 
   friend class IndexedReferencesExtractor;
   friend class GcSubrootsEnumerator;
   friend class RootsReferencesExtractor;
 
   DISALLOW_COPY_AND_ASSIGN(V8HeapExplorer);
@@ skipping 140 matching lines @@
 
   friend class HeapSnapshotJSONSerializerEnumerator;
   friend class HeapSnapshotJSONSerializerIterator;
 
   DISALLOW_COPY_AND_ASSIGN(HeapSnapshotJSONSerializer);
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_PROFILE_GENERATOR_H_