Support arbitrary PBS endpoints

[bretg]

Currently load-cookie.html only supports 'appnexus' and 'rubicon' endpoints. It's unfriendly for other PBS hosts to have to modify the cookieSync.js script.

Here's what the load-cookie invocation looks like:

https://PROVIDED_BY_HOSTCOMPANY/load-cookie.html?endpoint=HOSTCOMPANY

The proposal here is that we expand the values that the 'endpoint' parameter can accept:

• appnexus
• rubicon
• a url-encoded PBS URL. e.g. https%3A%2F%2Fprebid-server.example.com%2Fcookie_sync

validations:

• if the endpoint is not on the VALID_ENDPOINTS object, it must start with https

[premesh-freestar]

perhaps its better to have the "endpoint" value be custom and then support an additional optional param to pass the end point url. Further not that it matters but should we care if the url doesnt have cookie_sync in it ? if it loads the sync correctly it should be fine either way ?

[bretg]

Dropped the cookie_sync validation. I don't feel strongly about this interface. If you write the code, it can be whatever way you prefer. :-)

[bretg]

This was fixed in the PUC load-cookie.html a while back. Just documented the usage on https://docs.prebid.org/dev-docs/show-prebid-ads-on-amp-pages.html#user-sync