iOS embedder creates overlay layer based on platform view bounds but does not take clip bounds into account. #150646
Description
Running the ad benchmark app. In this case, there is nothing in the overlay layer, but we still present it.
We should have a mechanism to query EmbedderViewSlice or the DlCanvas to determine if there are any rendering ops in a layer (after culling) so that we can drop the layer entirely?
FYI @hellohuanlin / @flar