Code [here](https://github.com/ampproject/amphtml/blob/e00a3da988672d60fae47105c663793c1119e64a/src/ad-cid.js#L39) and [here](https://github.com/ampproject/amphtml/blob/e00a3da988672d60fae47105c663793c1119e64a/extensions/amp-analytics/0.1/cid-impl.js#L118) and [here](https://github.com/ampproject/amphtml/blob/e00a3da988672d60fae47105c663793c1119e64a/extensions/amp-analytics/0.1/cid-impl.js#L182) implies that we do not generate cookie for Ad CID. Is it a bug or working as intended? @avimehta @cramforce @dvoytenko @rudygalfi