The snapshotted plugin UI might have some custom appearance provided by the RenderTheme (for example). Allow the Injected Bundle to expose a title, subtitle and potentially come custom CSS for when the snapshot uses a shadow DOM.
Created attachment 184550 [details]
Comment on attachment 184550 [details]
Attachment 184550 [details] did not pass mac-wk2-ews (mac-wk2):
Created attachment 184555 [details]
Removed override keyword while I'm actually not overriding anything from the chrome client. That will happen in a subsequent commit.
Committed r140713: <http://trac.webkit.org/changeset/140713>