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

sky/sdk/BUILD.gn

 # 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("//mojo/public/dart/rules.gni")
 
 dart_pkg("sdk") {
   sources = [
     "CHANGELOG.md",
     "bin/init.dart",
@@ skipping 72 matching lines @@
     "lib/rendering/box.dart",
     "lib/rendering/flex.dart",
     "lib/rendering/object.dart",
     "lib/rendering/paragraph.dart",
     "lib/rendering/sky_binding.dart",
     "lib/rendering/stack.dart",
     "lib/sky_tool",
     "lib/theme/colors.dart",
     "lib/theme/edges.dart",
     "lib/theme/shadows.dart",
+    "lib/theme/theme_data.dart",
     "lib/theme/typography.dart",
     "lib/theme/view_configuration.dart",
     "lib/widgets/animated_component.dart",
     "lib/widgets/basic.dart",
     "lib/widgets/button_base.dart",
     "lib/widgets/checkbox.dart",
     "lib/widgets/dialog.dart",
     "lib/widgets/drawer.dart",
     "lib/widgets/drawer_header.dart",
     "lib/widgets/fixed_height_scrollable.dart",
     "lib/widgets/flat_button.dart",
     "lib/widgets/floating_action_button.dart",
     "lib/widgets/icon.dart",
     "lib/widgets/icon_button.dart",
     "lib/widgets/ink_well.dart",
     "lib/widgets/material.dart",
     "lib/widgets/material_button.dart",
     "lib/widgets/menu_divider.dart",
     "lib/widgets/menu_item.dart",
     "lib/widgets/modal_overlay.dart",
     "lib/widgets/navigator.dart",
     "lib/widgets/popup_menu.dart",
     "lib/widgets/popup_menu_item.dart",
     "lib/widgets/radio.dart",
     "lib/widgets/raised_button.dart",
     "lib/widgets/scaffold.dart",
     "lib/widgets/scrollable.dart",
     "lib/widgets/switch.dart",
+    "lib/widgets/theme.dart",
     "lib/widgets/toggleable.dart",
     "lib/widgets/tool_bar.dart",
     "lib/widgets/widget.dart",
     "pubspec.yaml",
   ]
 
   # List of mojom targets that the sky pkg exports
   deps = [
     "//sky/services/viewport",
   ]
 
   datadeps = [
     "//sky/services/testing:bindings",
     "//sky/engine/bindings",
   ]
 
   sdk_ext_directory = "$root_gen_dir/sky/bindings"
 }