It doesn't make any sense to show volume controls in AirPlay since they wouldn't affect the volume on the receiver.
<rdar://problem/33011931>
Created attachment 314049 [details] Patch
Comment on attachment 314049 [details] Patch Clearing flags on attachment: 314049 Committed r218891: <http://trac.webkit.org/changeset/218891>
All reviewed patches have been landed. Closing bug.