Just as an FYI: the promo would not appear again if it is dismissed early. 

Even if it was slated to appear a second time?

If triggering is set up to make it appear twice, then it would. But, early dismissal is not special cased. 

Two causes for this bug:
1. The Incognito Bubble is not set up to disappear in response to autorotation.
2. The NTP Bubble is asked to trigger twice. The FeatureEngagementTracker returns NO for the second trigger, so it does not appear twice. But, it still clears the presenter object, so the dismissAnimate call is ignored.

Will have fixes for these early next week. 

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/f3ff2bc6163afeebf80b5a2f969bd683eccf4451

commit f3ff2bc6163afeebf80b5a2f969bd683eccf4451
Author: Gregory Chatzinoff <gchatz@chromium.org>
Date: Fri Dec 15 01:19:26 2017

Fix autorotation dismissal for the User Education Bubbles.

Fix the lack of autorotation dismissal in the user education bubbles
by:
1. Ensuring that both the new tab and incognito bubbles are dismissed.
2. Ensuring that the presenter objects are not overwritten if the
presentation is triggered more than once.
3. Change dismissal due to autorotation not to be animated, since
animated dismissal does not look good during the rotation.

Bug:  767201 
Cq-Include-Trybots: master.tryserver.chromium.mac:ios-simulator-cronet;master.tryserver.chromium.mac:ios-simulator-full-configs
Change-Id: Ib30f03b061acd140ee8014b495087854d1e9e82e
Reviewed-on: https://chromium-review.googlesource.com/828143
Reviewed-by: edchin <edchin@chromium.org>
Commit-Queue: Gregory Chatzinoff <gchatz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#524278}
[modify] https://crrev.com/f3ff2bc6163afeebf80b5a2f969bd683eccf4451/ios/chrome/browser/ui/browser_view_controller.mm

Verified on iPhone X iOS 11.2, iPhone 7+ iOS 10.3.3, iPad Pro 12'5 iOs 11.2 on M65.0.3299.0Canary 
Product help bubble disappears when device is rotated.