Fix auto-refresh in Heap profile.

runtime/observatory/lib/src/elements/heap_profile.dart

Index: runtime/observatory/lib/src/elements/heap_profile.dart
===================================================================
--- runtime/observatory/lib/src/elements/heap_profile.dart	(revision 44977)
+++ runtime/observatory/lib/src/elements/heap_profile.dart	(working copy)
@@ -6,6 +6,7 @@
 
 import 'dart:html';
 import 'observatory_element.dart';
+import 'package:logging/logging.dart';
 import 'package:observatory/app.dart';
 import 'package:observatory/service.dart';
 import 'package:observatory/elements.dart';
@@ -102,13 +103,34 @@
     _subscription.cancel((){});
     super.detached();
   }
-
+  
+  // Keep at most one outstanding auto-refresh RPC.
+  bool refreshAutoPending = false;
+  bool refreshAutoQueued = false;
+  
   void _onEvent(ServiceEvent event) {
     if (autoRefresh && event.eventType == 'GC') {
-      refresh((){});
+      if (!refreshAutoPending) {
+        refreshAuto();
+      } else {
+        // Remember to refresh once more, to ensure latest profile.
+        refreshAutoQueued = true;
+      }
     }
   }
 
+  void refreshAuto() {
+    refreshAutoPending = true;
+    refreshAutoQueued = false;
+    refresh(() {
+      refreshAutoPending = false;
+      // Keep refreshing if at least one GC event was received while waiting.
+      if (refreshAutoQueued) {
+        refreshAuto();
+      }
+    });
+  }
+
   void _updatePieCharts() {
     assert(profile != null);
     _newPieDataTable.clearRows();