Add a new Theme widget to control color and text color of apps

R=abarth@chromium.org, abarth, hixie

Review URL: https://codereview.chromium.org/1194743003.

examples/stocks2/lib/stock_app.dart

@@ -3,8 +3,12 @@
 // found in the LICENSE file.
 
 import 'package:sky/rendering/sky_binding.dart';
+import 'package:sky/theme/colors.dart' as colors;
+import 'package:sky/theme/theme_data.dart';
+import 'package:sky/theme/typography.dart' as typography;
 import 'package:sky/widgets/basic.dart';
 import 'package:sky/widgets/navigator.dart';
+import 'package:sky/widgets/theme.dart';
 import 'package:sky/widgets/widget.dart';
 
 import 'stock_data.dart';
@@ -46,7 +50,10 @@ class StocksApp extends App {
   }
 
   Widget build() {
-    return new Navigator(_navigationState);
+    return new Theme(
+      data: new ThemeData(color: colors.Purple, text: typography.white),
+      child: new Navigator(_navigationState)
+    );
   }
 }
 

examples/stocks2/lib/stock_home.dart

@@ -169,8 +169,7 @@ class StockHome extends Component {
           new IconButton(
             icon: 'navigation/more_vert_white',
             onPressed: _handleMenuShow)
-        ],
-        backgroundColor: colors.Purple[500]
+        ]
       );
   }
 

examples/stocks2/lib/stock_settings.dart

@@ -3,13 +3,13 @@
 // found in the LICENSE file.
 
 import 'package:sky/theme/colors.dart' as colors;
-import 'package:sky/theme/typography.dart' as typography;
 import 'package:sky/widgets/basic.dart';
 import 'package:sky/widgets/checkbox.dart';
 import 'package:sky/widgets/icon_button.dart';
 import 'package:sky/widgets/menu_item.dart';
 import 'package:sky/widgets/navigator.dart';
 import 'package:sky/widgets/scaffold.dart';
+import 'package:sky/widgets/theme.dart';
 import 'package:sky/widgets/tool_bar.dart';
 
 class StockSettings extends Component {
@@ -30,8 +30,7 @@ class StockSettings extends Component {
       left: new IconButton(
         icon: 'navigation/arrow_back_white',
         onPressed: _navigator.pop),
-      center: new Text('Settings', style: typography.white.title),
-      backgroundColor: colors.Purple[500]
+      center: new Text('Settings', style: Theme.of(this).text.title)
     );
   }
 

examples/widgets/sector.dart

@@ -7,13 +7,15 @@ import 'dart:math' as math;
 import 'package:sky/rendering/box.dart';
 import 'package:sky/rendering/flex.dart';
 import 'package:sky/rendering/sky_binding.dart';
-import 'package:sky/theme/colors.dart';
+import 'package:sky/theme/colors.dart' as colors;
 import 'package:sky/theme/edges.dart';
-import 'package:sky/theme/typography.dart';
+import 'package:sky/theme/theme_data.dart';
+import 'package:sky/theme/typography.dart' as typography;
 import 'package:sky/widgets/basic.dart';
 import 'package:sky/widgets/material.dart';
 import 'package:sky/widgets/raised_button.dart';
 import 'package:sky/widgets/scaffold.dart';
+import 'package:sky/widgets/theme.dart';
 import 'package:sky/widgets/tool_bar.dart';
 import 'package:sky/widgets/widget.dart';
 
@@ -74,10 +76,11 @@ class SectorApp extends App {
   }
 
   Widget build() {
-    return new Scaffold(
+    return new Theme(
+      data: new ThemeData(color: colors.Blue, text: typography.white),
+      child: new Scaffold(
         toolbar: new ToolBar(
-          center: new Text('Sector Layout in a Widget Tree', style: white.title),
-          backgroundColor: Blue[500]),
+            center: new Text('Sector Layout in a Widget Tree', style: typography.white.title)),
         body: new Material(
           edge: MaterialEdge.canvas,
           child: new Flex([
@@ -131,6 +134,7 @@ class SectorApp extends App {
             justifyContent: FlexJustifyContent.spaceBetween
           )
         )
+      )
     );
   }
 }

examples/widgets/styled_text.dart

@@ -7,10 +7,12 @@ import 'package:sky/rendering/box.dart';
 import 'package:sky/rendering/flex.dart';
 import 'package:sky/rendering/sky_binding.dart';
 import 'package:sky/theme/colors.dart';
+import 'package:sky/theme/theme_data.dart';
 import 'package:sky/theme/typography.dart';
 import 'package:sky/widgets/basic.dart';
 import 'package:sky/widgets/material.dart';
 import 'package:sky/widgets/scaffold.dart';
+import 'package:sky/widgets/theme.dart';
 import 'package:sky/widgets/tool_bar.dart';
 import 'package:sky/widgets/widget.dart';
 
@@ -105,11 +107,13 @@ HAL: This mission is too important for me to allow you to jeopardize it.''';
       onPointerDown: toggleToTextFunction
     );
 
-    return new Scaffold(
+    return new Theme(
+      data: new ThemeData(color: Blue, text: white),
+      child: new Scaffold(
         body: new Material(child: interactiveBody),
         toolbar: new ToolBar(
-        center: new Text('Hal and Dave', style: white.title),
-        backgroundColor: Blue[500]
+          center: new Text('Hal and Dave', style: white.title)
+        )
       )
     );
   }