Final CL to kill off client/samples .

client/samples/swarm/UIState.dart

-// Copyright (c) 2011, 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.
-
-/**
- * The base class for UI state that intends to support browser history.
- */
-class UIState {
-  /**
-   * The event listener we hook to the window's "popstate" event.
-   * This event is triggered by the back button or by the first page load.
-   */
-  EventListener _historyTracking;
-
-  UIState();
-
-  void startHistoryTracking() {
-    stopHistoryTracking();
-
-    bool firstEvent = true;
-    _historyTracking = EventBatch.wrap((event) {
-      String state = window.location.hash;
-      if (state.startsWith('#')) {
-        // TODO(jimhug): Support default argument on substring.
-        state = state.substring(1, state.length);
-      }
-
-      if (firstEvent && state != '') {
-        // TODO(jmesserly): When loading a bookmark or refreshing, we replace
-        // the app state with a clean app state so the back button works. It
-        // would be better to support jumping to the previous story.
-        // We'd need to do some history manipulation here and some fixes to
-        // the views for this.
-        window.history.replaceState(null, document.title, '#');
-      } else if (state != '') {
-        loadFromHistory(JSON.parse(state));
-      }
-      firstEvent = false;
-    });
-
-    window.on.popState.add(_historyTracking);
-  }
-
-  void stopHistoryTracking() {
-    if (_historyTracking != null) {
-      window.on.popState.add(_historyTracking); // remove?
-    }
-  }
-
-  /** Pushes a state onto the browser history stack */
-  void pushToHistory() {
-    if (_historyTracking == null) {
-      throw 'history tracking not started';
-    }
-
-    String state = JSON.stringify(toHistory());
-
-    // TODO(jmesserly): [state] should be an Object, and we should pass it to
-    // the state parameter instead of as a #hash URL. Right now we're working
-    //  around b/4582542.
-    window.history.pushState(null, document.title, '#' + state);
-  }
-
-  /**
-   * Serialize the state to a form suitable for storing in browser history.
-   */
-  abstract Map<String, String> toHistory();
-
-  /**
-   * Load the UI state from the given [values].
-   */
-  abstract void loadFromHistory(Map<String, String> values);
-}