[EFL][WK2] Use C API inside ewk_file_chooser_request
https://bugs.webkit.org/show_bug.cgi?id=107811

Reviewed by Sam Weinig.

Use C API inside ewk_file_chooser_request instead of
accessing the internal C++ classes directly, to
avoid violating API layering.

* UIProcess/API/efl/ewk_file_chooser_request.cpp:
(EwkFileChooserRequest::EwkFileChooserRequest):
(EwkFileChooserRequest::~EwkFileChooserRequest):
(EwkFileChooserRequest::allowMultipleFiles):
(EwkFileChooserRequest::acceptedMIMETypes):
(EwkFileChooserRequest::cancel):
(EwkFileChooserRequest::chooseFiles):
(ewk_file_chooser_request_accepted_mimetypes_get):
(ewk_file_chooser_request_files_choose):
(ewk_file_chooser_request_file_choose):
* UIProcess/API/efl/ewk_file_chooser_request_private.h:
(EwkFileChooserRequest::create):
(EwkFileChooserRequest):
* UIProcess/efl/PageUIClientEfl.cpp:
(WebKit::PageUIClientEfl::runOpenPanel):


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@141709 268f45cc-cd09-0410-ab3c-d52691b4dbfc