[freeall]

The extension requires login to Ge.tt (it's free). And the Gmail login goes through the normal Google login.

What the extension does is to add a button to the page and when you click that files are uploaded to Ge.tt and a link is added to your email body. There's no exchange of any Google login needed.

[they4kman]

I don't mean the actual login to Google or Gmail; I mean the login form that pops up to login to Ge.tt when I click the button to upload to Ge.tt.

[freeall]

Ahh, ok. With the Ge.tt API you receive a token which is stored in local storage. So the pass is never stored locally.