title: Getting installed app size
body: <p>I'm trying to figure out how to get the size of an installed app.<br>
  What's already failed:<br>
  - <code>new File('/data/app/some.apk')</code> - reports incorrect size<br>
  - <code>PackageManager.getPackageSizeInfo(String packageName, IPackageStatsObserver observer)</code> - is <code>@hide</code> and relies on some obscure <code>IPackageStatsObserver</code> for result so I can't call it via reflection.</p>