I think, current 1P frame for Ctrl+\ , which shown at bottom left corner is not intuitive enough.
Better is to use mac-like layout : with centered frame, popped down from the center of addressbar. LIke Safari do.
As well as it is great idea to remove close button, which hides 1P frame, and create cancel button, which do same task. This frame is not window - why it needs close button?
And if it looks like window, it have close button like a window... I expect it to close by pressing Ctrl+F4 hotkey, as I do for closing any popup windows. But it don't close. Current Chrome tab closes. Very UX-frustrating.