Retrieves the MIME type of the resource pointed by uri.
In the event the URI cannot be found, NULL is returned and
error is set to G_BOOKMARK_FILE_ERROR_URI_NOT_FOUND. In the
event that the MIME type cannot be found, NULL is returned and
error is set to G_BOOKMARK_FILE_ERROR_INVALID_VALUE.
Since 2.12
Retrieves the MIME type of the resource pointed by uri. In the event the URI cannot be found, NULL is returned and error is set to G_BOOKMARK_FILE_ERROR_URI_NOT_FOUND. In the event that the MIME type cannot be found, NULL is returned and error is set to G_BOOKMARK_FILE_ERROR_INVALID_VALUE. Since 2.12