Facebook signin in Android has an option to enable Chrome Custom Tabs instead of the webview for the login dialog when the Facebook app is not installed. There should be an option to enable this.
This has two main advantages:
- Users don't have to re-enter their credentials each time since they're already logged into their Facebook accounts in Chrome most of the times.
- Better security since Chrome Custom Tabs is not a part of the app so the users don't have to worry about the app spying on their passwords.