Users are currently experiencing intermittent (and hard to debug) TLS
errors when loading the portal authentication page. This could be
caused by using http://www.gnome.org/ for our connectivity checks
because it redirects to HTTPS.
We can completely remove TLS from the equation by not using HTTPS.
http://nmcheck.gnome.org/ is a good choice because it doesn't redirect
to HTTPS and was created for NetworkManager's connectivity check.
https://bugzilla.gnome.org/show_bug.cgi?id=769940
We assumed that either a portal would give us a target URI, or we
would eventually reach the URI of our choice (which is http://www.gnome.org)
This is not always the case: even after a successful login we may
stay in a confirmation page, so make sure that every time we see a
redirect we trigger a connectivity check (or queue one for when
the user closes the window)
https://bugzilla.gnome.org/show_bug.cgi?id=733848
Add a small DBus-activated GtkApplication that embeds a WebKitWebView
and implements some minimal logic to see if the login succeeds.
It will try to connect to a custom NM-provided url (the portal login
page), if one exists, or to www.gnome.org in the normal case of
a portal doing redirect.
https://bugzilla.gnome.org/show_bug.cgi?id=704416
