Add support to PPID in <amp-ad type="doubleclick"> component

[demianrenzulli]

Describe the new feature or change to an existing feature you'd like to see

Publisher provided identifier (PPID) is a widely used feature by publishers using Google Ads, to send Google Ad Manager an identifier for use in frequency capping, audience segmentation and targeting, sequential ad rotation and other audience-based ad delivery controls across devices.

Currently there's no way of passing PPID to the component.

Describe alternatives you've considered

Discussing this with folks from the AMP team, the following solution was proposed:

"Provide support via remote config, since the AMP page would need to make a callout to the publisher to learn the publishers ID for this user.
Then, the publisher could provide url and return value as response body and would need to consider if domain of call-out should be restricted to canonical page URL."

Additional context

Forbes requested this feature as part of their mobile AMP-First site.

[demianrenzulli]

cc // @jeffjose @rjaponte

[demianrenzulli]

Gentle bump, folks any thoughts on the status of this FR?

cc // @jeffjose

[willhessel]

Publishers will start asking for this feature in the following months due to Privacy Sandbox / 3p cookie changes.
As part of their 1P data investments, PPID will be key priority in their implementation roadmaps for 2021.
I cannot mention publicly, but important Publishers have already asked for this feature.
So +1 (on behalf of huge publishers) to @demianrenzulli FR