Google calendar embed not working
| These are primarily notes|
It won't be complete in any sense.
It exists to contain fragments of useful information.
After a while, I discovered firebug mentioning
Load denied by X-Frame-Options: https://accounts.google.com/ServiceLogin...
So google is sending 
However, the point here isn't so much that it's using X-Frame-Options, because it makes no sense to use that on the calendar embed.
The problem is that google redirects you to ServiceLogin, which it only needs to do when you are not logged in.
...or, in my case, when the login-session cookie isn't ending up at google, which can happen when your browser flatly refuses all third-party cookies. As Firefox seems to do. My third-party-cookies setting was set to "Never", but I can't recall whether that's the default or I set that.