The experimental flag EnableNewClearBrowsingDataUI controls code that has not been touched since early december last year. Last modification was before upstreaming in https://chromereviews.googleplex.com/552217014
Experimental flags on iOS are on their way out (go/feature-flags-on-ios) and are migrating to chrome://flags.
This bug is to remove all related code from experimental_flags.mm and either replacing it with a base::Feature and a chrome://flags or to remove all the dead code (including a test that I had to disable as it sets the user default).
Comment 1 by msramek@chromium.org
, Aug 29 2017