Add new param in refererDetection to get top most referer

[robertrmartinez]

Type of issue

Feature request

Description

Some adapters are implementing their own functions to get the top most referer.

See here for details and example: #8261

We should add this into the referer object passed into bid adapters so they do not have to duplicate this code!

[dgirardi]

In what situation does it make sense to get the referrer to an iframe? isn't this just a bug with the current referrer detection?

Also related: #5637

[dgirardi]

Dug a little more, and I think this is a bug that has become a feature. In the simple case where Prebid is not running in a cross-origin iframe, the referer is set to window.top.location:

Prebid.js/src/refererDetection.js

Line 148 in 32f4a5c

foundReferrer = currentLocation;

There's no attempt to grab the actual referer as we do for iframes:

Prebid.js/src/refererDetection.js

Line 127 in 32f4a5c

const referrer = previousWindow.document.referrer;

adapters are relying on this behavior - made especially clear by code that effectively says "get the current location from refererInfo, but don't expect it to contain the referrer":

Prebid.js/modules/gmosspBidAdapter.js

Lines 172 to 190 in 32f4a5c

	function getUrl(refererInfo) {
	if (refererInfo && refererInfo.referer) {
	return refererInfo.referer;
	}
	try {
	return getWindowTop.location.href;
	} catch (e) {
	return getWindowLocation.href;
	}
	}
	function getReferrer() {
	try {
	return getWindowTop.document.referrer;
	} catch (e) {
	return document.referrer;
	}
	}

I'll try to address this with a breaking change for prebid 7 (#5637), but I'm not sure what we can do for 6 - I think most adapters are getting the wrong values if Prebid is running in an iframe.

[patmmccann]

tracking on #5637