Expose last seen heap object id via v8 public api.

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 631 matching lines @@
 
   void SnapshotGenerationFinished();
   SnapshotObjectId FindEntry(Address addr);
   SnapshotObjectId FindOrAddEntry(Address addr, unsigned int size);
   void MoveObject(Address from, Address to);
   SnapshotObjectId last_assigned_id() const {
     return next_id_ - kObjectIdStep;
   }
 
   void StopHeapObjectsTracking();
-  void PushHeapObjectsStats(OutputStream* stream);
+  SnapshotObjectId PushHeapObjectsStats(OutputStream* stream);
 
   static SnapshotObjectId GenerateId(v8::RetainedObjectInfo* info);
   static inline SnapshotObjectId GetNthGcSubrootId(int delta);
 
   static const int kObjectIdStep = 2;
   static const SnapshotObjectId kInternalRootObjectId;
   static const SnapshotObjectId kGcRootsObjectId;
   static const SnapshotObjectId kNativesRootObjectId;
   static const SnapshotObjectId kGcRootsFirstSubrootId;
   static const SnapshotObjectId kFirstAvailableObjectId;
@@ skipping 37 matching lines @@
   DISALLOW_COPY_AND_ASSIGN(HeapObjectsMap);
 };
 
 
 class HeapSnapshotsCollection {
  public:
   HeapSnapshotsCollection();
   ~HeapSnapshotsCollection();
 
   bool is_tracking_objects() { return is_tracking_objects_; }
-  void PushHeapObjectsStats(OutputStream* stream) {
+  SnapshotObjectId PushHeapObjectsStats(OutputStream* stream) {
     return ids_.PushHeapObjectsStats(stream);
   }
   void StartHeapObjectsTracking() { is_tracking_objects_ = true; }
   void StopHeapObjectsTracking() { ids_.StopHeapObjectsTracking(); }
 
   HeapSnapshot* NewSnapshot(
       HeapSnapshot::Type type, const char* name, unsigned uid);
   void SnapshotGenerationFinished(HeapSnapshot* snapshot);
   List<HeapSnapshot*>* snapshots() { return &snapshots_; }
   HeapSnapshot* GetSnapshot(unsigned uid);
@@ skipping 371 matching lines @@
 
   friend class HeapSnapshotJSONSerializerEnumerator;
   friend class HeapSnapshotJSONSerializerIterator;
 
   DISALLOW_COPY_AND_ASSIGN(HeapSnapshotJSONSerializer);
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_PROFILE_GENERATOR_H_