The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/bc269b60efe34705a28d1015fc4fd8c5512357a7

commit bc269b60efe34705a28d1015fc4fd8c5512357a7
Author: Eugene But <eugenebut@google.com>
Date: Fri Mar 16 22:33:13 2018

Fix Download Manager autolayout issue.

Download Manager has the following UI elements:
 - state icon
 - status text (f.e. <File Name> 10 MB)
 - action button (f.e. Download)
 - close button

Status text width is highly variable and often does not fit the UI. So
status text width should be flexible and action button width should be
constant.

This sets setContentCompressionResistancePriority: for status label to
UILayoutPriorityDefaultLow.

Bug:  822768 
Cq-Include-Trybots: master.tryserver.chromium.mac:ios-simulator-cronet;master.tryserver.chromium.mac:ios-simulator-full-configs
Change-Id: I9505511e7d3a1a8dbcf22c7df406530cb270c55a
Reviewed-on: https://chromium-review.googlesource.com/966794
Commit-Queue: Eugene But <eugenebut@chromium.org>
Reviewed-by: edchin <edchin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#543849}
[modify] https://crrev.com/bc269b60efe34705a28d1015fc4fd8c5512357a7/ios/chrome/browser/ui/download/download_manager_view_controller.mm

Issue reopen 
Version: Chrome Canary 67.0.3376.0
Device: iPhone 6 Plus
iOS: 11.2.6

There are two UI elements hidden after orientation change.
1. State icon
2. Close button

This two elements remain hidden after download has finished ("Open in...")

https://drive.google.com/open?id=1MvVNMawgNH98tMz1Uqa0kUL6dkBL395S

Screenshot 
https://drive.google.com/open?id=1ul0ZSjNLqNZhszDjdZg_TAhtGzRNwUyP

Thanks! Issue described in comment #3 is crbug.com/823698. This one was about resized action button label, so I will close it.

Issue verified 
Version: Chrome Beta  67.0.3393.19 
Device: iPhone 6
iOS: 11.2.6

Thanks for clarifying. This fix is about correct button size.
Note that issues mentioned in comment #3 are also fixed
https://drive.google.com/open?id=1WKBGuybiGqqyFU1pcJOWVa1Jxsmu0Gjt
https://drive.google.com/open?id=1-SB2KZJDM4Nc2awIyTcR40c96mB8SDJs
https://drive.google.com/open?id=12qsyXfj0-y5zxyWUqqNyK00xrWCmEAAs
https://drive.google.com/open?id=1BrPR_yfgtc9OT1bp-iWySJM0-oFU_Afn