🌸 Cherry-pick request for #30285 into #2009142129000 (Approved)

[zhouyx]

Cherry-pick request

Issue	PR	Beta / Experimental?	Stable?	LTS?	Release issue
#30285	#30284	Only AMPHTML Ad Beta	No	No	#<RELEASE_ISSUE>

Why does this issue meet the cherry-pick criteria?

#30285 caused visibility loss when an inabox ad resize in viewport

Why is a Beta / Experimental cherry-pick not needed?

We're only cherrypicking to the AMPHTML ad release version, since it's not affecting AMP documents. (No resize within viewport)

Mini-postmortem

Summary

We recently added a check to element's size before sending visibility request. This lead to an issue when an element resize without intersectionRatio change.

Impact

This leads to visibility loss for inabox ads that resize from 0 within the viewport.

Action Items

• Revert the change to add size zero change
• Add the size check back, but for the inabox case add 'resize' listener to the iframe window
• Have visibility trigger listen to both InteresectionObserver and ResizeObserver if possible

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/cc @ampproject/release-on-duty @ampproject/wg-approvers @ampproject/cherry-pick-approvers

to @ampproject/wg-ads @jeffkaufman @lannka @powerivq

[zhouyx]

#30284 has been merged.

[zhouyx]

cherry-pick to AMPHTML ad release only. to @lannka for approval. cc @jeffkaufman

[lannka]

approved

[zhouyx]

version 2009142129001 has been released. Will promote it to inabox RC next Monday during business hours.

[zhouyx]

2009142129001 has been released to inabox RC.