Kill onDidMount()/onDidUnmount() in favour of just overriding the relevant methods.

sky/sdk/lib/framework/components2/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 '../animation/animated_value.dart';
 import '../fn2.dart';
 import '../theme2/colors.dart';
 import '../theme2/shadows.dart';
 import 'animated_component.dart';
 import 'dart:async';
@@ skipping 39 matching lines @@
   }
 }
 
 class PopupMenu extends AnimatedComponent {
 
   PopupMenu({ Object key, this.controller, this.items, this.level })
       : super(key: key) {
     animate(controller.position, (double value) {
       _position = value;
     });
-    // onDidMount(_measureSize);
   }
 
   PopupMenuController controller;
   List<List<UINode>> items;
   int level;
 
   void syncFields(PopupMenu source) {
     controller = source.controller;
     items = source.items;
     level = source.level;
@@ skipping 16 matching lines @@
   // String _inlineStyle() {
   //   if (_position == null || _position == 1.0 ||
   //       _height == null || _width == null)
   //     return null;
   //   return '''
   //     opacity: ${math.min(1.0, _position * 3.0)};
   //     width: ${math.min(_width, _width * (0.5 + _position * 2.0))}px;
   //     height: ${math.min(_height, _height * _position * 1.5)}px;''';
   // }
 
+  // void didMount() {
+  //   _measureSize();
+  //   super.didMount();
+  // }
+
   // void _measureSize() {
   //   setState(() {
   //     var root = getRoot();
   //     _width = root.width.round();
   //     _height = root.height.round();
   //   });
   // }
 
   UINode build() {
     int i = 0;
     List<UINode> children = new List.from(items.map((List<UINode> item) {
       double opacity = _opacityFor(i);
       return new PopupMenuItem(key: i++, children: item, opacity: opacity);
     }));
 
     // inlineStyle: _inlineStyle(),
     return new ShrinkWrapWidth(
       child: new Container(
         padding: const EdgeDims.all(8.0),
         decoration: new BoxDecoration(
           backgroundColor: Grey[50],
           borderRadius: 2.0,
           boxShadow: Shadow[level]),
         child: new BlockContainer(children: children)
       )
     );
   }
 
 }