Detect 3rd party cookies and show an error screen

[ozten]

Sets a cookie during the /provision request.

Tests for cookie during the /signin request. If not present, displays this screen:

Link goes to https://support.mozilla.org/en-US/kb/enable-and-disable-cookies-website-preferences?esab=a&s=3rd+party+cookies&r=2&as=s

[ozten]

Force pushed 2 changes - fixed production domain name. Fixed unit test.

[callahad]

Could this conflict in any way with the change (mozilla/persona#3690) that Shane merged into core to detect and warn about cookie settings?

[ozten]

It could "conflict" from a UX perspective. I wasn't able to test end to end.

My hunch is that messaging in the IdP is better even if you are informed twice.

If this patch can ship before the next train, then we could always remove it later.

[ozten]

Blocked this morning for dev testing by lack of dev env. Per @karlht and @edmoz we'll merge, release to stage and play with it there.

[mostlygeek]

@ozten isn't merging your own PR sort of like editing your own wikipedia entry? :)