Wire up popup menus to back button

sky/sdk/lib/widgets/popup_menu.dart

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 import 'dart:math' as math;
 import 'dart:sky' as sky;
 
 import 'package:sky/animation/animation_performance.dart';
 import 'package:sky/painting/box_painter.dart';
 import 'package:sky/theme/colors.dart';
 import 'package:sky/theme/shadows.dart';
 import 'package:sky/widgets/animated_component.dart';
 import 'package:sky/widgets/basic.dart';
+import 'package:sky/widgets/navigator.dart';
 import 'package:sky/widgets/popup_menu_item.dart';
 import 'package:sky/widgets/scrollable_viewport.dart';
 
 const Duration _kMenuDuration = const Duration(milliseconds: 300);
 double _kMenuCloseIntervalEnd = 2.0 / 3.0;
 const double _kMenuWidthStep = 56.0;
 const double _kMenuMargin = 16.0; // 24.0 on tablet
 const double _kMenuMinWidth = 2.0 * _kMenuWidthStep;
 const double _kMenuMaxWidth = 5.0 * _kMenuWidthStep;
 const double _kMenuHorizontalPadding = 16.0;
 const double _kMenuVerticalPadding = 8.0;
 
 enum PopupMenuStatus {
   active,
   inactive,
 }
 
 typedef void PopupMenuStatusChangedCallback(PopupMenuStatus status);
 
 class PopupMenu extends AnimatedComponent {
 
   PopupMenu({
     String key,
     this.showing,
     this.onStatusChanged,
     this.items,
-    this.level
+    this.level,
+    this.navigator
   }) : super(key: key);
 
   bool showing;
   PopupMenuStatusChangedCallback onStatusChanged;
   List<PopupMenuItem> items;
   int level;
+  Navigator navigator;
 
   AnimatedType<double> _opacity;
   AnimatedType<double> _width;
   AnimatedType<double> _height;
   List<AnimatedType<double>> _itemOpacities;
   AnimatedList _animationList;
   AnimationPerformance _performance;
 
   void initState() {
     _performance = new AnimationPerformance()
@@ skipping 15 matching lines @@
         _close();
     }
     onStatusChanged = source.onStatusChanged;
     if (level != source.level) {
       level = source.level;
       _updateBoxPainter();
     }
     if (items.length != source.items.length)
       _updateAnimationVariables();
     items = source.items;
+    navigator = source.navigator;
     super.syncFields(source);
   }
 
   void _updateAnimationVariables() {
     double unit = 1.0 / (items.length + 1.5); // 1.0 for the width and 0.5 for the last item's fade.
     _opacity = new AnimatedType<double>(0.0, end: 1.0);
     _width = new AnimatedType<double>(0.0, end: 1.0, interval: new Interval(0.0, unit));
     _height = new AnimatedType<double>(0.0, end: 1.0, interval: new Interval(0.0, unit * items.length));
     _itemOpacities = new List<AnimatedType<double>>();
     for (int i = 0; i < items.length; ++i) {
@@ skipping 16 matching lines @@
       backgroundColor: Grey[50],
       borderRadius: 2.0,
       boxShadow: shadows[level]));
   }
 
   PopupMenuStatus get _status => _opacity.value != 0.0 ? PopupMenuStatus.active : PopupMenuStatus.inactive;
 
   PopupMenuStatus _lastStatus;
   void _checkForStateChanged() {
     PopupMenuStatus status = _status;
-    if (_lastStatus != null && status != _lastStatus && onStatusChanged != null)
-      onStatusChanged(status);
+    if (_lastStatus != null && status != _lastStatus) {
+      if (status == PopupMenuStatus.inactive &&
+          navigator != null && 
+          navigator.currentRoute.key == this)
+        navigator.pop();
+      if (onStatusChanged != null)
+        onStatusChanged(status);
+    }
     _lastStatus = status;
   }
 
+
   void _open() {
     _animationList.interval = null;
     _performance.play();
+    if (navigator != null)
+      navigator.pushState(this, (_) => _close());
   }
 
   void _close() {
     _animationList.interval = new Interval(0.0, _kMenuCloseIntervalEnd);
     _performance.reverse();
   }
 
   BoxPainter _painter;
 
   Widget build() {
@@ skipping 29 matching lines @@
                 )
               )
             )
           )
         )
       )
     );
   }
 
 }