UserAgent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/62.0.3202.94 Safari/537.36

Steps to reproduce the problem:
1. Middle-click a link to a page that requires HTTP Basic Authentication (to open it in a background tab).
2. Once the request completes, switch to the tab.
3. Without using the mouse, enter a username/password.
4. Realise you can't.

What is the expected behavior?
When the tab gains focus, the username field should gain focus automatically, like what happens if a Basic Auth page opens in the current tab.

What went wrong?
When switching to a previously unfocused tab, the focus is not on the username field by default, which is inconsistent with how the dialog behaves if it appears when the tab is focused, and there's no way to switch focus to the username field without clicking on it.

Did this work before? N/A 

Chrome version: 62.0.3202.94  Channel: stable
OS Version: Ubuntu 16.04.3
Flash Version: 27.0.0.187

Example Basic Auth link: https://httpbin.org/basic-auth/user/passwd