When specifying a new create histogram callback, reset all histograms so they recreate themselves o…

src/v8-counters.cc

Index: src/v8-counters.cc
diff --git a/src/v8-counters.cc b/src/v8-counters.cc
index b5a40b57cc3676e9cf33430b8076a34e2608ddac..36b45e2f8e8449d2a7d0636b88121ea924a4e697 100644
--- a/src/v8-counters.cc
+++ b/src/v8-counters.cc
@@ -93,4 +93,14 @@ Counters::Counters() {
   }
 }
 
+void Counters::ResetHistograms() {
+#define HT(name, caption) name##_.Reset();
+    HISTOGRAM_TIMER_LIST(HT)
+#undef HT
+
+#define HP(name, caption) name##_.Reset();
+    HISTOGRAM_PERCENTAGE_LIST(HP)
+#undef HP
+}
+
 } }  // namespace v8::internal