Layers panel show the following for a composited scroller:
  'Composition due to association with an element with a "overflow-scrolling: touch" style'

This is actually pretty outdated. Blink no longer supports overflow-scrolling css attribute and in fact we do not promote due to that. There are many signals that will be used when deciding to promote a overflow scroll container to be composited. I don't think we need or want to explain all that in Layers panel but perhaps just update the message to no longer reference overflow-scrolling: touch. Perhaps:

"Composition due to association with a scroll container that can support composited scrolling."


Actually the enum value kCompositingReasonOverflowScrollingTouch is also a bit of misnomer given that it is no longer limited to touch scrolling. May want to fix that as well at some point.