At least when hovered upon (with a mouse or pointer) that vertical ellipsis shows both a grey disk and the text "Customize and control Google Chrome". Happily,

At least when hovered upon (with a mouse or pointer) that vertical ellipsis shows both a grey disk and the text "Customize and control Google Chrome". Happily, that suggests one could click on it and not directly invoke an unwanted operation. I don't know the equivalent works for phone or tablet users with no such thing (AFAIK) as hover. To me, that's a problem with such interfaces beyond the hamburger icon.