title: Android - best practices for authorization
body: <p>I am researching how to autenticate and authorize user within Android application</p>
  
  <p>For autentication there is the AccountManager but I am not sure how to check whether the user is signed in or not. I know how to set up AccountAuthenticatorActivity and AuthenticatorService but I am not sure how its connected with the application.</p>
  
  <p>Am I supposed to call some check on every onCreate in every activity to ensure that the user is signed in or does the service does that for me somehow?</p>
  
  <p>If I am supposed to do some regular checking, what is the best practice towards where such checking should be called?</p>