Summary

Historically, Adsense implemented the full-width responsive tags(Auto Responsive and Core Responsive) to serve AMP users assuming that most users would be mobile users, and that publishers would have canonical pages to sereve desktop uers. As its name suggested, full-width responsive will occupy the width of the viewport, and expand the Ads. This would not work for the desktop users on AMP.

As more publishers use their AMP websites to serve desktop users, these responsive expansion logic created broken full-width experience to the desktop users. This ticket is to add a new flow to the expansion logic for Auto Responsive Tag and Core Responsive Tag.

Design document

For the Auto Responsive Tag and Core Responsive Tag to serve both mobile and desktop users, we need to implement a new flow for the Ad Size Expansion logic.

Check out this design doc for more details.

/cc @ampproject/wg-approvers, @calebcordry