This extension deletes browser data when all windows in a profile are closed.
This is basically incognito mode without losing your profile settings, such as the DevTools position and size. This extension deletes browser data when all windows in a profile are closed.
** Do not install this extension unless this is exactly what you want, and do not install this on your main profile. I will not be held accountable (nor care), if you install this, ignore the warning, and lose your browsing data. **
You will be able to choose which bits of browsing data is deleted when closing all windows in the current profile. By default, everything is deleted except for Form Data, History, and Passwords. It should go without saying that this extension is useless in incognito mode.
I recommend that you also install a theme for your development profile to easily distinguish windows from your main profile.
Source code: https://github.com/tweekmonster/Developer-Profile