Allow Observatory to run as a hosted web service

runtime/bin/vmservice/client/lib/src/app/settings.dart

Index: runtime/bin/vmservice/client/lib/src/app/settings.dart
diff --git a/runtime/bin/vmservice/client/lib/src/app/settings.dart b/runtime/bin/vmservice/client/lib/src/app/settings.dart
new file mode 100644
index 0000000000000000000000000000000000000000..2a7bbb37dd983043cb4f3fb3123a6fa07afec899
--- /dev/null
+++ b/runtime/bin/vmservice/client/lib/src/app/settings.dart
@@ -0,0 +1,45 @@
+// Copyright (c) 2014, 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 app;
+
+/// Static settings database.
+class _Settings {
+  static Storage _storage = window.localStorage;
+
+  /// Associated [value] with [key]. [value] must be JSON encodable.
+  static void set(String key, dynamic value) {
+    _storage[key] = JSON.encode(value);
+  }
+
+  /// Get value associated with [key]. Return value will be a JSON encodable
+  /// object.
+  static dynamic get(String key) {
+    var value = _storage[key];
+    if (value == null) {
+      return null;
+    }
+    return JSON.decode(value);
+  }
+}
+
+/// A group of settings each prefixed with group name and a dot.
+class SettingsGroup {
+  /// Group name
+  final String group;
+
+  SettingsGroup(this.group);
+
+  String _fullKey(String key) => '$group.$key';
+
+  void set(String key, dynamic value) {
+    var fullKey = _fullKey(key);
+    _Settings.set(fullKey, value);
+  }
+
+  dynamic get(String key) {
+    var fullKey = _fullKey(key);
+    return _Settings.get(fullKey);
+  }
+}