diff --git a/src/profiler/sampler.h b/src/profiler/sampler.h
index 354e935..8e8ef1c 100644
--- a/src/profiler/sampler.h
+++ b/src/profiler/sampler.h
@@ -34,12 +34,13 @@
   TickSample()
       : state(OTHER),
         pc(NULL),
-        external_callback(NULL),
+        external_callback_entry(NULL),
         frames_count(0),
         has_external_callback(false),
+        update_stats(true),
         top_frame_type(StackFrame::NONE) {}
   void Init(Isolate* isolate, const v8::RegisterState& state,
-            RecordCEntryFrame record_c_entry_frame);
+            RecordCEntryFrame record_c_entry_frame, bool update_stats);
   static void GetStackSample(Isolate* isolate, const v8::RegisterState& state,
                              RecordCEntryFrame record_c_entry_frame,
                              void** frames, size_t frames_limit,
@@ -48,7 +49,7 @@
   Address pc;      // Instruction pointer.
   union {
     Address tos;   // Top stack value (*sp).
-    Address external_callback;
+    Address external_callback_entry;
   };
   static const unsigned kMaxFramesCountLog2 = 8;
   static const unsigned kMaxFramesCount = (1 << kMaxFramesCountLog2) - 1;
@@ -56,6 +57,7 @@
   base::TimeTicks timestamp;
   unsigned frames_count : kMaxFramesCountLog2;  // Number of captured frames.
   bool has_external_callback : 1;
+  bool update_stats : 1;  // Whether the sample should update aggregated stats.
   StackFrame::Type top_frame_type : 4;
 };
 
@@ -98,12 +100,12 @@
   }
 
   // Used in tests to make sure that stack sampling is performed.
-  unsigned js_and_external_sample_count() const {
-    return js_and_external_sample_count_;
-  }
+  unsigned js_sample_count() const { return js_sample_count_; }
+  unsigned external_sample_count() const { return external_sample_count_; }
   void StartCountingSamples() {
-      is_counting_samples_ = true;
-      js_and_external_sample_count_ = 0;
+    js_sample_count_ = 0;
+    external_sample_count_ = 0;
+    is_counting_samples_ = true;
   }
 
   class PlatformData;
@@ -123,9 +125,10 @@
   base::Atomic32 has_processing_thread_;
   base::Atomic32 active_;
   PlatformData* data_;  // Platform specific data.
+  // Counts stack samples taken in various VM states.
   bool is_counting_samples_;
-  // Counts stack samples taken in JS VM state.
-  unsigned js_and_external_sample_count_;
+  unsigned js_sample_count_;
+  unsigned external_sample_count_;
   DISALLOW_IMPLICIT_CONSTRUCTORS(Sampler);
 };