I'd like to add HeapSnapshot::GetMaxSnapshotJSObjectId function.

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 17 matching lines @@
 #ifndef V8_PROFILE_GENERATOR_H_
 #define V8_PROFILE_GENERATOR_H_
 
 #include "allocation.h"
 #include "hashmap.h"
 #include "../include/v8-profiler.h"
 
 namespace v8 {
 namespace internal {
 
-typedef uint32_t SnapshotObjectId;
-
 class TokenEnumerator {
  public:
   TokenEnumerator();
   ~TokenEnumerator();
   int GetTokenId(Object* token);
 
   static const int kNoSecurityToken = -1;
   static const int kInheritsSecurityToken = -2;
 
  private:
@@ skipping 590 matching lines @@
   HeapSnapshotsCollection* collection() { return collection_; }
   Type type() { return type_; }
   const char* title() { return title_; }
   unsigned uid() { return uid_; }
   HeapEntry* root() { return root_entry_; }
   HeapEntry* gc_roots() { return gc_roots_entry_; }
   HeapEntry* natives_root() { return natives_root_entry_; }
   HeapEntry* gc_subroot(int index) { return gc_subroot_entries_[index]; }
   List<HeapEntry*>* entries() { return &entries_; }
   size_t raw_entries_size() { return raw_entries_size_; }
+  SnapshotObjectId max_snapshot_js_object_id() const {
+    return max_snapshot_js_object_id_;
+  }
 
   void AllocateEntries(
       int entries_count, int children_count, int retainers_count);
   HeapEntry* AddEntry(HeapEntry::Type type,
                       const char* name,
                       SnapshotObjectId id,
                       int size,
                       int children_count,
                       int retainers_count);
   HeapEntry* AddRootEntry(int children_count);
@@ skipping 20 matching lines @@
   const char* title_;
   unsigned uid_;
   HeapEntry* root_entry_;
   HeapEntry* gc_roots_entry_;
   HeapEntry* natives_root_entry_;
   HeapEntry* gc_subroot_entries_[VisitorSynchronization::kNumberOfSyncTags];
   char* raw_entries_;
   List<HeapEntry*> entries_;
   bool entries_sorted_;
   size_t raw_entries_size_;
+  SnapshotObjectId max_snapshot_js_object_id_;
 
   friend class HeapSnapshotTester;
 
   DISALLOW_COPY_AND_ASSIGN(HeapSnapshot);
 };
 
 
 class HeapObjectsMap {
  public:
   HeapObjectsMap();
@@ skipping 456 matching lines @@
 
   friend class HeapSnapshotJSONSerializerEnumerator;
   friend class HeapSnapshotJSONSerializerIterator;
 
   DISALLOW_COPY_AND_ASSIGN(HeapSnapshotJSONSerializer);
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_PROFILE_GENERATOR_H_