Gio points out in https://codereview.chromium.org/1841763002/#msg5 that it'd be nice to let people keep experimenting with the Web Bluetooth API even if we have to turn it off for all Origin Trial users. Currently, there's no way to test the kill switch in that situation (https://groups.google.com/a/chromium.org/d/topic/experimentation-dev/U7IAlXkWxoE/discussion), but we should add one.