A parental control add-on knows what sites are adult (ProCon Latte)
and a privacy mode add-on does not save browsing data (Stealther). You
can manually not save adult site browsing data, but if you forget it
once, you will have to erase all history. I deleted a folder that was
going to show me my most visited sites, I can't use an add-on that
gives me "direct access to my most visited sites" (Speed DIal) and I
can't use an add-on that gets me a "quick glance on the sites you use
the most, by period of the day" (New Tab King). The problem is that I
share my computer with my parents and my sister.