Add initial semi-working producers profile.

src/log.h

Index: src/log.h
diff --git a/src/log.h b/src/log.h
index 07a0429ace19895a167a9d54f86ab8332720e546..13d45d2e325769f61dd9bb1e263cb3cb9af69e67 100644
--- a/src/log.h
+++ b/src/log.h
@@ -223,6 +223,8 @@ class Logger {
                                            int number, int bytes);
   static void HeapSampleJSRetainersEvent(const char* constructor,
                                          const char* event);
+  static void HeapSampleJSProducerEvent(const char* constructor,
+                                        Address* stack);
   static void HeapSampleStats(const char* space, const char* kind,
                               int capacity, int used);