Add FlatButton

sky/sdk/lib/widgets/material_button.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 '../theme2/colors.dart';
-import '../theme2/edges.dart';
 import 'basic.dart';
 import 'button_base.dart';
 import 'ink_well.dart';
 import 'material.dart';
 
-enum RaisedButtonTheme { light, dark }
+// Rather than using this class directly, please use FlatButton or RaisedButton.
+abstract class MaterialButton extends ButtonBase {
 
-class RaisedButton extends ButtonBase {
-
-  RaisedButton({
+  MaterialButton({
     String key,
     this.child,
     this.enabled: true,
-    this.onPressed,
-    this.theme: RaisedButtonTheme.light
+    this.onPressed
   }) : super(key: key);
 
   Widget child;
   bool enabled;
   Function onPressed;
-  RaisedButtonTheme theme;
 
-  void syncFields(RaisedButton source) {
+  void syncFields(MaterialButton source) {
     child = source.child;
     enabled = source.enabled;
     onPressed = source.onPressed;
-    theme = source.theme;
     super.syncFields(source);
   }
 
+  Color get color;
+  int get level;
+
   Widget buildContent() {
     Widget contents = new Container(
       padding: new EdgeDims.symmetric(horizontal: 8.0),
       child: new Center(child: child) // TODO(ianh): figure out a way to compell the child to have gray text when disabled...
     );
-    Color color;
-    if (enabled) {
-      switch (theme) {
-        case RaisedButtonTheme.light:
-          if (highlight)
-            color = Grey[350];
-          else
-            color = Grey[300];
-          break;
-        case RaisedButtonTheme.dark:
-          if (highlight)
-            color = Blue[700];
-          else
-            color = Blue[600];
-          break;
-      }
-    } else {
-      color = Grey[350];
-    }
     return new EventListenerNode(
       new Container(
         height: 36.0,
-        constraints: new BoxConstraints(minWidth: 88.0),
-        margin: new EdgeDims.all(4.0),
+        constraints: new BoxConstraints(minWidth: 88.0,
+                                        minHeight: 36.0,
+                                        maxHeight: 36.0),
+        margin: new EdgeDims.all(8.0),
         child: new Material(
-          edge: MaterialEdge.card,
           child: enabled ? new InkWell(child: contents) : contents,
-          level: enabled ? (highlight ? 2 : 1) : 0,
+          level: level,
           color: color
         )
       ),
       onGestureTap: (_) { if (onPressed != null && enabled) onPressed(); }
     );
   }
 
 }