Add --print-metrics vm flag for printing metrics to console

runtime/vm/isolate.cc

Index: runtime/vm/isolate.cc
diff --git a/runtime/vm/isolate.cc b/runtime/vm/isolate.cc
index 7af37bfbcff69f3d9213c7ee37e0aa812b6ec5b6..0b8a1b07a09d5fdcc2b199c1f08edff5e9d95aed 100644
--- a/runtime/vm/isolate.cc
+++ b/runtime/vm/isolate.cc
@@ -44,7 +44,7 @@
 
 namespace dart {
 
-DECLARE_FLAG(charp, timeline_trace_dir);
+DECLARE_FLAG(bool, print_metrics);
 
 DEFINE_FLAG(bool, trace_isolates, false,
             "Trace isolate creation and shut down.");
@@ -1540,6 +1540,15 @@ void Isolate::Shutdown() {
       OS::Print("[-] Stopping isolate:\n"
                 "\tisolate:    %s\n", name());
     }
+    if (FLAG_print_metrics) {
+      LogBlock lb(this);
+      ISL_Print("Printing metrics for %s\n", name());
+#define ISOLATE_METRIC_PRINT(type, variable, name, unit)                       \
+  ISL_Print("%s\n", metric_##variable##_.ToString());
+  ISOLATE_METRIC_LIST(ISOLATE_METRIC_PRINT);
+#undef ISOLATE_METRIC_PRINT
+      ISL_Print("\n");
+    }
   }
 
 #if defined(DEBUG)