title: How to grant permission to files not owned by application
body: <p>When trying to send files not created by my app to Firebase Storage, I get an exception with the message <strong>"/path/to/the/file permission denied"</strong>.  </p>
  
  <p>However, when I create in my code a file in the internal directory of my app (<em>/data/data/package_name/files/</em>) and send it to the Firebase storage it works.</p>
  
  <p><strong><em>How to send other files located elsewhere in the internal storage without troubles ?</em></strong></p>