Enable PA API module on cookie-less inventory only

[zhuoli-fledge]

As suggested in WICG/turtledove#1345, there is a way to enable PAAPI only on cookie-less inventory. This is expected to help increase the publisher adoption of Protected Audience API.

According to the Prebid PA API Module documentation, publishers can choose whether to enable the PAAPI module by the ‘enabled’ setting which is set to ‘false’ by default.

The feature request here is to extend existing module configuration to support enabling the PA API module for cookie-less inventory only.

Possible potential solutions are:

• Option 1: Add “enableForCookieless” flag. When publishers set “enableForCookieless” to true, PA API is always enabled on cookieless inventory regardless of the “enabled” flag.

• Option 2: Add “scope” parameter to the configuration. With values like “global”, “cookieless only”, “cookieless pa api inventory only” so that the publishers can choose when to enable the module. The “enabled” flag shall work with the “scope” parameter and only enable PA API when

  • The “enabled” flag is true, and
  • The inventory matches with the “scope” parameter.

Note: We can also change the default value to make the module enabled by default on cookieless inventory where we have PA API interest groups available.

Details on how to detect cookieless inventory as well as how to detect presence of interest groups is discussed in https://github.com/WICG/turtledove/issues/1345.