Handle .onions in all contexts

Description

It seems generally unlikely that anyone entering a .onion address into the address bar means to browse to that site without Tor or to make DNS requests regarding it. When someone does so, we should probably treat it as an oversight. At the very least, we should not tell anyone else about it (no DNS lookups, for instance). But perhaps we should do more and provide a useful notification or even smoothly redirect them to a Private Window with Tor?

Design

Show a “Open in Tor” button in the URL bar when user enters a .onion address or address with .onion available.

Dark Theme

Dark theme is supported:

Assets

Figma: https://www.figma.com/file/5THkuEtO2Ewn9LfqrHZP9a/?node-id=0%3A1

[tomlowenthal]

I’m embarrassed that I didn’t think of this before. I think it makes sense to treat .onion sites just like any other site if you open it in a non-private window. No need to make a big deal out of it, just quietly use Tor behind the scenes and modify the security indicator to indicate that Brave is relying on the onion protocol rather than HTTPS.

[librarymd]

Supporting .onion addresses in all contexts would be a game-changer for Brave as a browser. There is no browser doing that yet. To be honest, having a separate private Tor window is too much hassle. There is already TorBrowser as a separate window. Navigating privacy friendly .onion addresses should be as easy as navigating normal web, not harder.