Delete drawerController and make drawer handle back behavior natively

sky/sdk/example/fitness/lib/settings.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 'package:sky/widgets/basic.dart';
 import 'package:sky/widgets/drawer_item.dart';
 import 'package:sky/widgets/switch.dart';
 import 'package:sky/widgets/icon_button.dart';
 import 'package:sky/widgets/material.dart';
 import 'package:sky/widgets/navigator.dart';
 import 'package:sky/widgets/scaffold.dart';
+import 'package:sky/widgets/scrollable_viewport.dart';
 import 'package:sky/widgets/tool_bar.dart';
 import 'package:sky/widgets/theme.dart';
 
 import 'fitness_types.dart';
 
 typedef void SettingsUpdater({
   BackupMode backup
 });
 
 class SettingsFragment extends Component {
@@ skipping 16 matching lines @@
       left: new IconButton(
         icon: "navigation/arrow_back",
         onPressed: navigator.pop),
       center: new Text('Settings')
     );
   }
 
   Widget buildSettingsPane() {
     return new Material(
       type: MaterialType.canvas,
-      child: new Container(
-        padding: const EdgeDims.symmetric(vertical: 20.0),
-        child: new Block([
-          new DrawerItem(
-            onPressed: () { _handleBackupChanged(!(backup == BackupMode.enabled)); },
-            children: [
-              new Flexible(child: new Text('Back up data to the cloud')),
-              new Switch(value: backup == BackupMode.enabled, onChanged: _handleBackupChanged)
-            ]
-          ),
-          new DrawerItem(
-            children: [
-              new Block([
-                new Text('Height'),
-                new Text("6'2\"", style: Theme.of(this).text.caption),
-              ])
-            ]
-          ),
-        ])
+      child: new ScrollableViewport(
+        child: new Container(
+          padding: const EdgeDims.symmetric(vertical: 20.0),
+          child: new Block([
+            new DrawerItem(
+              onPressed: () { _handleBackupChanged(!(backup == BackupMode.enabled)); },
+              children: [
+                new Flexible(child: new Text('Back up data to the cloud')),
+                new Switch(value: backup == BackupMode.enabled, onChanged: _handleBackupChanged)
+              ]
+            ),
+            new DrawerItem(
+              children: [
+                new Flex([
+                  new Text('Height'),
+                  new Text("6'2\"", style: Theme.of(this).text.caption),
+                ], direction: FlexDirection.vertical, alignItems: FlexAlignItems.start)
+              ]
+            ),
+          ])
+        )
       )
     );
   }
 
   Widget build() {
     return new Scaffold(
       toolbar: buildToolBar(),
       body: buildSettingsPane()
     );
   }
 }