In case of ephemeral data manager we are initializing the policy but not setting it in the WebsiteDataStore.
Created attachment 409543 [details] Patch
Thanks for the patch. If this patch contains new public API please make sure it follows the guidelines for new WebKit2 GTK+ API. See https://trac.webkit.org/wiki/WebKitGTK/AddingNewWebKit2API
Created attachment 409544 [details] Patch
Committed r267524: <https://trac.webkit.org/changeset/267524>