google-chrome

[Linux for blind general discussion]

I find that usually pressing either f6 or shift+f6 1 or two times will 
cycle through to the alert. From there I have access via the tab key to 
the buttons on the alert. Failing this, usually alerts are permission 
requests, and most of those can be set from the site settings button 
that you should be able to find if you go to the bottom of a page and 
press the tab key. Hope it helps.

~Kyle