Ed, PTAL.

 Issue 862072  has been merged into this issue.

thegreenfrog@ is helping out and taking a look at this. 

There are a couple of other rotation symptoms that have been reported:

 - In tab grid landscape, swipe from incognito tabs to recent tabs, rotate back to portrait, then swipe back to incognito. Grid is under toolbar and doesn’t move. 

 - Notch on iPhone X covers tab switcher preview when in landscape mode.

Please test any fixes against those cases as well, and (if needed) file additional bugs so we're sure we're getting everything taken care of.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/8fcdc1716a6bd7bc78c3080bf05ab1de366ec7d5

commit 8fcdc1716a6bd7bc78c3080bf05ab1de366ec7d5
Author: Chris Lu <thegreenfrog@chromium.org>
Date: Thu Jul 19 18:37:59 2018

[ios] Fix TabGrid rotation bug for iPhoneX regarding SafeArea Management

CollectionViewControllers within a ScrollView do not have accurate safe area guides. So this CL manages the proper safe area insets manually through contentInset.
TableViews do manage it better, but only on sides in which they area attached to the scrollview. On sides that are not, it is not predictable.

- removes CollectionView use of safe area by setting UIScrollViewContentInsetAdjustmentNever.
- adds ScrollView safe area insets (which is always accurate) to contentInset to viewWillLayoutSubviews.
- maintains TableView safe area management defaults, but ensure that the leading safe area inset matches the scrollView's.

Videos:
(iPhoneX)https://drive.google.com/open?id=1NhGQL441TgwxEOxwmelGPoUE2aI6Lg5r
(iPhone7 iOS 10)https://drive.google.com/open?id=1RYMcO_ZthbAAv2qWtVJIqBlXKTNgJgub
(iPad iOS 11)https://drive.google.com/open?id=1ZX9kl4j8UHcluHwa6LHYXCyI2ANaKyJP


Bug:  860437 

Change-Id: Ie622fb58c7a86c09d3bff23e73908b9f33bc659c
Reviewed-on: https://chromium-review.googlesource.com/1135945
Reviewed-by: Gauthier Ambard <gambard@chromium.org>
Reviewed-by: edchin <edchin@chromium.org>
Reviewed-by: Kurt Horimoto <kkhorimoto@chromium.org>
Commit-Queue: Kurt Horimoto <kkhorimoto@chromium.org>
Commit-Queue: Chris Lu <thegreenfrog@chromium.org>
Cr-Commit-Position: refs/heads/master@{#576569}
[modify] https://crrev.com/8fcdc1716a6bd7bc78c3080bf05ab1de366ec7d5/ios/chrome/browser/ui/tab_grid/grid/grid_view_controller.mm
[modify] https://crrev.com/8fcdc1716a6bd7bc78c3080bf05ab1de366ec7d5/ios/chrome/browser/ui/tab_grid/tab_grid_view_controller.mm

https://drive.google.com/file/d/13UwpwGFERc6hMwmjxJot-y_kFxSX9gTW/view?usp=sharing
Tested on iPhone X iOS 11.4 . The misalignment is still see for a few secs when the device orientation is changed.