Update charted to 0.4.8 and roll

packages/usage/example/ga.dart

 // Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
-/**
- * A simple command-line app to hand-test the usage library.
- */
+/// A simple command-line app to hand-test the usage library.
 library usage_ga;
 
 import 'package:usage/usage_io.dart';
 
-void main(List args) {
+main(List args) async {
   final String DEFAULT_UA = 'UA-55029513-1';
 
   if (args.isEmpty) {
     print('usage: dart ga <GA tracking ID>');
     print('pinging default UA value (${DEFAULT_UA})');
   } else {
     print('pinging ${args.first}');
   }
 
   String ua = args.isEmpty ? DEFAULT_UA : args.first;
 
-  Analytics ga = new AnalyticsIO(ua, 'ga_test', '1.0');
-  ga.optIn = true;
+  Analytics ga = new AnalyticsIO(ua, 'ga_test', '3.0');
 
-  ga.sendScreenView('home').then((_) {
-    return ga.sendScreenView('files');
-  }).then((_) {
-    return ga.sendException('foo exception, line 123:56');
-  }).then((_) {
-    return ga.sendTiming('writeDuration', 123);
-  }).then((_) {
-    return ga.sendEvent('create', 'consoleapp', label: 'Console App');
-  }).then((_) {
-    print('pinged ${ua}');
-  });
+  await ga.sendScreenView('home');
+  await ga.sendScreenView('files');
+  await ga
+      .sendException('foo error:\n${sanitizeStacktrace(StackTrace.current)}');
+  await ga.sendTiming('writeDuration', 123);
+  await ga.sendEvent('create', 'consoleapp', label: 'Console App');
+  print('pinged ${ua}');
+
+  await ga.waitForLastPing();
+
+  ga.close();
 }