title: Can findViewById(android.R.id.content) ever return null for Snackbars?
body: <p>I want to be able to display Snackbars but I am confused by this notion that I have to supply it with a View. You'd think it'd allow you to display the Snackbar at the bottom of the screen by default, but maybe I am missing something.</p>
  
  <p>Anyway supposedly this can be done by using the view:</p>
  
  <p><code>findViewById(android.R.id.content)</code></p>
  
  <p>However I get a warning that this may be null even though it always seems to work wherever I try it. When can it possibly be null? </p>