Add counters that automatically track object sizes and counts.

src/heap.h

Index: src/heap.h
diff --git a/src/heap.h b/src/heap.h
index 8d9adb02dbe9b3d8cbcc106d2bfdb9a1e59bae40..08c91a41d2a755e41f4ad33c8025ec34c0235380 100644
--- a/src/heap.h
+++ b/src/heap.h
@@ -1600,6 +1600,14 @@ class Heap {
     global_ic_age_ = (global_ic_age_ + 1) & SharedFunctionInfo::ICAgeBits::kMax;
   }
 
+  void RecordObjectStats(InstanceType type, size_t size) {
+    ASSERT(type <= LAST_TYPE);
+    object_counts_[type]++;
+    object_sizes_[type] += size;
+  }
+
+  void CheckpointObjectStats();
+
  private:
   Heap();
 
@@ -1993,11 +2001,18 @@ class Heap {
 
   void AdvanceIdleIncrementalMarking(intptr_t step_size);
 
+  void ClearObjectStats(bool clear_last_time_stats = false);
 
   static const int kInitialSymbolTableSize = 2048;
   static const int kInitialEvalCacheSize = 64;
   static const int kInitialNumberStringCacheSize = 256;
 
+  // Object counts and used memory by InstanceType
+  size_t object_counts_[LAST_TYPE + 1];
+  size_t object_counts_last_time_[LAST_TYPE + 1];
+  size_t object_sizes_[LAST_TYPE + 1];
+  size_t object_sizes_last_time_[LAST_TYPE + 1];
+
   // Maximum GC pause.
   int max_gc_pause_;