Expose last seen heap object id via v8 public api.

include/v8-profiler.h

Index: include/v8-profiler.h
diff --git a/include/v8-profiler.h b/include/v8-profiler.h
index 8f380f2094daef623204390b9f73e3c1b5f5ecae..5f560c37eae8425cca4553f6fa01be21e3de3ead 100644
--- a/include/v8-profiler.h
+++ b/include/v8-profiler.h
@@ -448,11 +448,12 @@ class V8EXPORT HeapProfiler {
    * reports updates for all previous time intervals via the OutputStream
    * object. Updates on each time interval are provided as a stream of the
    * HeapStatsUpdate structure instances.
+   * The return value of the function is the last seen heap object Id.
    *
    * StartHeapObjectsTracking must be called before the first call to this
    * method.
    */
-  static void PushHeapObjectsStats(OutputStream* stream);
+  static SnapshotObjectId PushHeapObjectsStats(OutputStream* stream);
 
   /**
    * Stops tracking of heap objects population statistics, cleans up all