Applies to all OS except mobile, writing this for M70+ 

There are two different ways to access the Omnibox depending on OS: ctrl + l or F6/ctrl + back or forward arrow keys. 

If using ctrl + l, pressing tab brings you to the main page content. 
If using F6/ctrl + arrow keys, pressing tab brings you to any outstanding dialogs, the quick bookmark icon, extensions, etc. 

I feel that this can be hard to discover and can be confusing. I'm requesting either documentation or some other way that this difference be made clear to keyboard only users. Perhaps we could do a keyboard navigation tutorial?