The recent sandboxing changes to whitelist only specific XPC services was too restrictive for the Plugin process. This prevents Flash from being able to display a File Browser.
Created attachment 322914 [details]
Comment on attachment 322914 [details]
Clearing flags on attachment: 322914
Committed r222984: <http://trac.webkit.org/changeset/222984>
All reviewed patches have been landed. Closing bug.