Android Handler

https://medium.com/@jagsaund/android-handler-internals-b5d49eba6977#.u5tb8qf2b

http://grepcode.com/file/repository.grepcode.com/java/ext/com.google.android/android/5.1.1_r1/android/os/Looper.java#Looper.setMessageLogging%28android.util.Printer%29

https://developer.android.com/reference/android/os/Handler.html#getLooper()