Steps to reproduce:
1. In about:settings, add several IMEs to your list of available IMEs. 
2. Open the IME detailed view from the Ash system menu.
3. Press ctrl+shift+space to switch IMEs until you switch to one that is currently not visible (i.e., outside of the scrollable area).

What happens:
The selected IME name remains not visible to the user.

What should happen instead:
The IME list should auto-scroll so that the currently-selected IME is visible to the user.

 Issue 675516  tracks the same bug but for the opt-in IME menu.