Converted Observatory class-view element

runtime/observatory/lib/src/repositories/top_retaining_instances.dart

+// Copyright (c) 2016, 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
+
+part of repositories;
+
+class TopRetainingInstancesRepository
+    implements M.TopRetainingInstancesRepository {
+  Future<Iterable<M.RetainingObject>> get(M.IsolateRef i, M.ClassRef c) async {
+    S.Isolate isolate = i as S.Isolate;
+    S.Class cls = c as S.Class;
+    assert(isolate != null);
+    assert(cls != null);
+    final raw = await isolate.fetchHeapSnapshot(true).last;
+    final snapshot = new HeapSnapshot();
+    await snapshot.loadProgress(isolate, raw).last;
+    return (await Future.wait(snapshot.getMostRetained(isolate,
+                                                      classId: cls.vmCid,
+                                                      limit: 10)))
+           .map((object) => new S.RetainingObject(object));
+  }
+}