Initial GUI for review

runtime/bin/vmservice/client/observatory/packages/observatory/src/observatory/isolate_manager.dart

Index: runtime/bin/vmservice/client/observatory/packages/observatory/src/observatory/isolate_manager.dart
diff --git a/runtime/bin/vmservice/client/observatory/packages/observatory/src/observatory/isolate_manager.dart b/runtime/bin/vmservice/client/observatory/packages/observatory/src/observatory/isolate_manager.dart
new file mode 100644
index 0000000000000000000000000000000000000000..b35dddabd0d227f0c1299ab9a268d82db8a26d70
--- /dev/null
+++ b/runtime/bin/vmservice/client/observatory/packages/observatory/src/observatory/isolate_manager.dart
@@ -0,0 +1,38 @@
+part of observatory;
+
+class IsolateManager extends ObservableMixin {
+  ObservatoryApplication _application;
+  ObservatoryApplication get application => _application;
+
+  @observable final Map<int, Isolate> isolates =
+      toObservable(new Map<int, Isolate>());
+
+  static bool _foundIsolateInMembers(int id, List<Map> members) {
+    return members.any((E) => E['id'] == id);
+  }
+
+  void _updateIsolates(List<Map> members) {
+    // Find dead isolates.
+    var deadIsolates = [];
+    isolates.forEach((k, v) {
+      if (!_foundIsolateInMembers(k, members)) {
+        deadIsolates.add(k);
+      }
+    });
+    // Remove them.
+    deadIsolates.forEach((k) {
+      print('Removing ${isolates[k]}');
+      isolates.remove(k);
+    });
+    // Add new isolates.
+    members.forEach((k) {
+      var id = k['id'];
+      var name = k['name'];
+      if (isolates[id] == null) {
+        var isolate = new Isolate(id, name);
+        print('Adding $isolate');
+        isolates[id] = isolate;
+      }
+    });
+  }
+}