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

sky/sdk/lib/theme/theme_data.dart

Index: sky/sdk/lib/theme/theme_data.dart
diff --git a/base/test/malloc_wrapper.cc b/sky/sdk/lib/theme/theme_data.dart
similarity index 50%
copy from base/test/malloc_wrapper.cc
copy to sky/sdk/lib/theme/theme_data.dart
index eb280a3eeea52f49e534c7c5e3f6f7a40e80a750..f5873978d49ff311f1c059d6dbd377a6f9021b30 100644
--- a/base/test/malloc_wrapper.cc
+++ b/sky/sdk/lib/theme/theme_data.dart
@@ -2,10 +2,12 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-#include "malloc_wrapper.h"
+import 'dart:sky';
 
-#include <stdlib.h>
+import 'typography.dart';
 
-void* MallocWrapper(size_t size) {
-  return malloc(size);
+class ThemeData {
+  const ThemeData({ this.text, this.color });
+  final TextTheme text;
+  final Map<int, Color> color;
 }