Introduce a way to grab heap stats.

src/heap-profiler.h

Index: src/heap-profiler.h
diff --git a/src/heap-profiler.h b/src/heap-profiler.h
index ef5c4f4b4a0d4e3546247d6a3d34e639a165bd0d..2308674784fca352e1a1145624466777bf210f39 100644
--- a/src/heap-profiler.h
+++ b/src/heap-profiler.h
@@ -44,8 +44,6 @@ class HeapSnapshotsCollection;
     }                                                                        \
   } while (false)
 
-// The HeapProfiler writes data to the log files, which can be postprocessed
-// to generate .hp files for use by the GHC/Valgrind tool hp2ps.
 class HeapProfiler {
  public:
   static void SetUp();
@@ -57,6 +55,10 @@ class HeapProfiler {
   static HeapSnapshot* TakeSnapshot(String* name,
                                     int type,
                                     v8::ActivityControl* control);
+
+  static void StartHeapObjectsTracking();
+  static void StopHeapObjectsTracking();
+  static void PushHeapObjectsStats(OutputStream* stream);
   static int GetSnapshotsCount();
   static HeapSnapshot* GetSnapshot(int index);
   static HeapSnapshot* FindSnapshot(unsigned uid);
@@ -84,6 +86,10 @@ class HeapProfiler {
                                  v8::ActivityControl* control);
   void ResetSnapshots();
 
+  void StartHeapObjectsTrackingImpl();
+  void StopHeapObjectsTrackingImpl();
+  void PushHeapObjectsStatsImpl(OutputStream* stream);
+
   HeapSnapshotsCollection* snapshots_;
   unsigned next_snapshot_uid_;
   List<v8::HeapProfiler::WrapperInfoCallback> wrapper_callbacks_;