isSafeFrame detection not detecting AMP forced SafeFrame

[Sir-Will]

Describe the bug
While testing an integration in AMP environment, I encountered the issue of it not resizing the iframe. It turns out that the isSafeFrame check does not work for the forced SafeFrame by AMP.

The moment SafeFrame is being enabled in GAM, the detection works.

prebid-universal-creative/src/environment.js

Lines 26 to 28 in 907ca91

	export function isSafeFrame(win) {
	return !!(win.$sf && win.$sf.ext);
	}

The only workaround seems to be to create dedicated line items and creatives for AMP, which has SafeFrame enabled in GAM.

It might make sense to always send the resize message for AMP, if there is no possibility without SafeFrame.

prebid-universal-creative/src/mobileAndAmpRender.js

Line 65 in 907ca91

if (isSafeFrame(window)) {

To Reproduce
Steps to reproduce the behavior:

1. AMP environment page
2. Serve GAM creative with SafeFrame off
3. Set breakpoint on isSafeFrame, in amp.js
4. See it resulting in false and iframe src containing "safeframe" URL

Expected behavior
Outgoing AMP embed-siz message when the creative does not have SafeFrame checked.

[patmmccann]

related: #107

the solution would close both i imagine

[dgirardi]

#249 should produce the expected behavior in the OP:

Outgoing AMP embed-size message when the creative does not have SafeFrame checked.

However, I cannot get it to actually resize the ad. I don't know if that's what it's supposed to do; in the safeframe case the resizing is done by the $sf API calls which are not available in the forced safeframe case. The only embed-size documentation I can find are related to the amp-iframe tag and specify some requirements for it (resizable attribute & allow-same-origin), but just translating those into amp-ad does not appear to work.

Also, I could not find any way to detect an AMP environment. Our logic always runs in what looks like any other safeframe.

[patmmccann]

Also, I could not find any way to detect an AMP environment. Our logic always runs in what looks like any other safeframe.

did #107 or ampproject/amphtml#6829 not help?

[dgirardi]

No, window.name is empty so that snippet's

var version = JSON.parse(decodeURI(window.name)).ampcontextVersion;

does not work. I suspect there's something I don't know regarding how to set up the AMP page, the creative, or both.