ATF amp-iframe inside Shadow DOM not working on Safari

[gilbertococchi]

ATF Amp-Iframe with a Placeholder inside a Sticky Element is not working and triggers error

dom.js:645 amp-iframe is not used for displaying fixed ad. Please use amp-sticky-ad and amp-ad instead.

Steps to Reproduce:

• Visita Page https://www.repstatic.it/cless/main/rep21/2017-v1/poc/video-iframe-blocked.html from Safari Mobile, Real Device or simulator, also reproducible on Chrome Mobile Safari Emulation.
• Click on audio icon on the bottom right corner.

Screenshot with error below:

It works fine on Chrome Mobile and other browsers, it seems a iOS specific issue.

Previously reported in #18563

@iwoak @nainar

[wassgha]

I can not reproduce this, I can see the sticky audio when clicking the sound button

[gilbertococchi]

Hi Wassim, the issue is reproducible on large iOS devices such as "iPhone 6/7/8 Plus" Chrome Mobile UA emulation, or the Real Device but it has to be a Plus Screen iOS device and/or the Simulator.

The issue seems to be related with some viewport detection we apply to fixed Iframes here on large devices that triggers the error on iOS Plus devices only: https://github.com/ampproject/amphtml/issues/18563

Do you think we can change this logic to allow a non Ad usage of an ATF Amp-Iframe provided with a Placeholder to accomodate this?

[wassgha]

Investigated this and as per #3863 amp-iframe is essentially matching the size of the iframe to traditional ad sizes to detect whether the iframe is an ad or not (not sure if that's the optimal thing to do but given that we have no idea what content of an iframe would be considered an ad...) so a quick fix would be to play around with sizes different than a regular ad to circumvent this check. Not sure if we can do better than that, cc @jridgewell .

https://github.com/ampproject/amphtml/blob/ad497ca6f4bfb6b3ef0de2afa1bc7c10da0f502a/src/iframe-helper.js#L545-L563

[wassgha]

(to clarify, the issue is not Safari, it's the device's screen size)

[wassgha]

/cc @jridgewell on this

[jridgewell]

We can remove the restriction, it just needs an I2I and approval.

[omerr132]

@jridgewell Any update on this? As of now we still get iframes blocked with this error message.

I'm not sure why - but this happens only to iframes that are inside lightboxes. The same iframe on the page itself doesn't get blocked .

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