Most of us (me, anyway) throw that away. It is the feed for the chain oiler. Has nothing to do with anything else.
The oiler was discontinued pre-K8. Don't know exactly what they did other than do away with the visible oiler adjustment on the exterior. Maybe Honda threw out that pan as well, as its not needed. They went to an ORing chain, which requires far less maintenance than a non-ORing chain.
Just a quick wipedown and squirt every 500 miles or so.