Incoming references service request and UI.

runtime/bin/vmservice/observatory/lib/src/elements/inbound_reference.dart

Index: runtime/bin/vmservice/observatory/lib/src/elements/inbound_reference.dart
diff --git a/runtime/bin/vmservice/observatory/lib/src/elements/inbound_reference.dart b/runtime/bin/vmservice/observatory/lib/src/elements/inbound_reference.dart
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index 0000000000000000000000000000000000000000..cb738b5662d45e774c2355fe0db8e72279daa884
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+++ b/runtime/bin/vmservice/observatory/lib/src/elements/inbound_reference.dart
@@ -0,0 +1,49 @@
+// Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+library inbound_reference_element;
+
+import 'dart:async';
+import 'package:polymer/polymer.dart';
+import 'package:observatory/service.dart';
+import 'service_ref.dart';
+
+@CustomTag('inbound-reference')
+class InboundReferenceElement extends ServiceRefElement {
+  InboundReferenceElement.created() : super.created();
+
+  dynamic get slot => ref['slot'];
+  bool get slotIsArrayIndex => slot is num;
+  bool get slotIsField => slot is ServiceMap && slot['type'] == '@Field';
+
+  ServiceObject get source => ref['source'];
+
+  // I.e., inbound references to 'source' for recursive pointer chasing.
+  @observable ObservableList inboundReferences;
+  Future<ServiceObject> fetchInboundReferences(arg) {
+    return source.isolate.get(source.id + "/inbound_references?limit=$arg")
+        .then((ServiceMap response) {
+          inboundReferences = new ObservableList.from(response['references']);
+        });
+  }
+
+  // TODO(turnidge): This is here to workaround vm/dart2js differences.
+  dynamic expander() {
+    return expandEvent;
+  }
+ 
+  void expandEvent(bool expand, var done) {
+    assert(ref is ServiceMap);
+    if (expand) {
+      fetchInboundReferences(100).then((result) {
+        notifyPropertyChange(#ref, 0, 1);
+      }).whenComplete(done);
+    } else {
+      ServiceMap refMap = ref;
+      refMap['fields'] = null;
+      refMap['elements'] = null;
+      done();
+    }
+  }
+}