Converted Observatory heap-snapshot element

runtime/observatory/lib/src/models/repositories/heap_snapshot.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 models;
+
+enum HeapSnapshotLoadingStatus {
+  fetching,
+  loading,
+  loaded
+}
+
+bool isHeapSnapshotProgressRunning(HeapSnapshotLoadingStatus status) {
+  switch (status) {
+    case HeapSnapshotLoadingStatus.fetching:
+    case HeapSnapshotLoadingStatus.loading:
+      return true;
+    default:
+      return false;
+  }
+}
+
+abstract class HeapSnapshotLoadingProgressEvent {
+  HeapSnapshotLoadingProgress get progress;
+}
+
+abstract class HeapSnapshotLoadingProgress {
+  HeapSnapshotLoadingStatus get status;
+  String get stepDescription;
+  double get progress;
+  Duration get fetchingTime;
+  Duration get loadingTime;
+  HeapSnapshot get snapshot;
+}
+
+abstract class HeapSnapshotRepository {
+  Stream<HeapSnapshotLoadingProgressEvent> get(IsolateRef isolate,
+                                               {bool gc: false});
+}