This functionality has been broken since r99364, which stopped setting the "webkit-resource" property needed by ewk_protocol_handler_soup.cpp. After giving it some thought, it looks clear that this code should not be in ewk at all: it is very backend-specific (even in the function signatures it expects), and it only allows callers to register schemes once and provide a single handler to all of them, which does not make much sense.
Created attachment 117468 [details] Proposed patch
CC'ing mrobinson; this should fix the issue discussed on IRC a few weeks ago in which r99364 removed our custom handler code in ewk.
Comment on attachment 117468 [details] Proposed patch Clearing flags on attachment: 117468 Committed r101726: <http://trac.webkit.org/changeset/101726>
All reviewed patches have been landed. Closing bug.