We are working on a proposal to allow a frame to allow delegating a user gesture from an embedder to an embeddee. In other words, to allow a main frame to delegate to an iframe. This API is to answer for some features that start requiring a user gesture on the document in order to be used like the Vibration API or autoplay in some browsers. The intent is to prevent the embeddee to request to run as part of the embedder; we would like to make sure the embedders have the right tools to avoid this situation.
The repository is available here: https://github.com/mounirlamouri/gesture-delegation/blob/master/README.md
The explainer with more details and a concrete proposal is available here: https://github.com/mounirlamouri/gesture-delegation/blob/master/explainer.md