Yes, probably caused by the switch to MacViews.

 Issue 884987  has been merged into this issue.

I believe I have a fix: <https://chromium-review.googlesource.com/c/chromium/src/+/1268396>. It introduces a graphical glitch while deminiaturizing windows though.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/129abeac557646a4c99fdc9f27b00989b7fd36c1

commit 129abeac557646a4c99fdc9f27b00989b7fd36c1
Author: Elly Fong-Jones <ellyjones@chromium.org>
Date: Tue Oct 16 13:25:07 2018

mac: fix restoring minimized windows

This change:
1) Has BridgedNativeWidgetHostImpl notify the owning Widget when it becomes
   minimized
2) Has session restore not activate minimized browser windows when selecting
   a restored tab
3) Has session restore not show a newly created browser window if it's
   minimized

restore save; without this change, the widget will not get saved as minimized.
window. On Mac, showing/activating a window implies de-minimizing it, so this
is required to avoid de-minimizing saved minimized windows, but I think it is
necessary on other platforms as well.

Test steps:
1) Start Chromium
2) Create a second browser window (cmd-n) and minimize it
3) In the first window, chrome://restart

Before this change, both browser windows appear after restart; after this
change, the first window appears and the second stays minimized.

Note that there is a graphical glitch when first restoring a window that is
minimized this way: the window paints as blank for a few frames while running
the deminiaturize animation.

Bug:  888218 
Change-Id: I8ac121408336a7d6aeedd2b27cd2c9c9d20a18f2
Reviewed-on: https://chromium-review.googlesource.com/c/1268396
Reviewed-by: Scott Violet <sky@chromium.org>
Commit-Queue: Elly Fong-Jones <ellyjones@chromium.org>
Cr-Commit-Position: refs/heads/master@{#599961}
[modify] https://crrev.com/129abeac557646a4c99fdc9f27b00989b7fd36c1/chrome/browser/sessions/session_restore_browsertest_chromeos.cc
[modify] https://crrev.com/129abeac557646a4c99fdc9f27b00989b7fd36c1/chrome/browser/ui/browser_tabrestore.cc
[modify] https://crrev.com/129abeac557646a4c99fdc9f27b00989b7fd36c1/ui/views/cocoa/bridged_native_widget_host_impl.mm
[modify] https://crrev.com/129abeac557646a4c99fdc9f27b00989b7fd36c1/ui/views/widget/native_widget_mac.mm

ccameron@, sdy@: can you take a peek at the graphical glitch mentioned in the CL description? I don't know how to fix that.

My guess would be that we're setting the ui::Compositor to be locked when minimized at some level. It's not clear that we do that from a quick look at the code, but it should be find-able.

Did the cocoa browser have that glitch?

It wouldn't have -- it didn't use a ui::Compositor to draw UI.

#10: Can you take a peek? :)

I want to soak this on canary for a couple of days, but requesting merge to M71.

Your change meets the bar and is auto-approved for M71. Please go ahead and merge the CL to branch 3578 manually. Please contact milestone owner if you have questions.
Owners: benmason@(Android), kariahda@(iOS), kbleicher@(ChromeOS), govind@(Desktop)

For more details visit https://www.chromium.org/issue-tracking/autotriage - Your friendly Sheriffbot

Pls merge your change to M71 branch #3578 ASAP so we can pick it up for next M71 Beta release. Thank you.

Pls merge your change to M71 branch 3578 latest by 1:00 PM PT, Monday, 10/22 so we can pick it up for next week beta release. Thank you. 

Merged: https://chromium-review.googlesource.com/c/chromium/src/+/1293551

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/f474595943481cff06bb6fc23ce5f1464c39b515

commit f474595943481cff06bb6fc23ce5f1464c39b515
Author: Elly Fong-Jones <ellyjones@chromium.org>
Date: Mon Oct 22 12:56:12 2018

mac: fix restoring minimized windows

This change:
1) Has BridgedNativeWidgetHostImpl notify the owning Widget when it becomes
   minimized
2) Has session restore not activate minimized browser windows when selecting
   a restored tab
3) Has session restore not show a newly created browser window if it's
   minimized

restore save; without this change, the widget will not get saved as minimized.
window. On Mac, showing/activating a window implies de-minimizing it, so this
is required to avoid de-minimizing saved minimized windows, but I think it is
necessary on other platforms as well.

Test steps:
1) Start Chromium
2) Create a second browser window (cmd-n) and minimize it
3) In the first window, chrome://restart

Before this change, both browser windows appear after restart; after this
change, the first window appears and the second stays minimized.

Note that there is a graphical glitch when first restoring a window that is
minimized this way: the window paints as blank for a few frames while running
the deminiaturize animation.

Bug:  888218 
Change-Id: I8ac121408336a7d6aeedd2b27cd2c9c9d20a18f2
Reviewed-on: https://chromium-review.googlesource.com/c/1268396
Reviewed-by: Scott Violet <sky@chromium.org>
Commit-Queue: Elly Fong-Jones <ellyjones@chromium.org>
Cr-Original-Commit-Position: refs/heads/master@{#599961}(cherry picked from commit 129abeac557646a4c99fdc9f27b00989b7fd36c1)
Reviewed-on: https://chromium-review.googlesource.com/c/1293551
Reviewed-by: Elly Fong-Jones <ellyjones@chromium.org>
Cr-Commit-Position: refs/branch-heads/3578@{#203}
Cr-Branched-From: 4226ddf99103e493d7afb23a4c7902ee496108b6-refs/heads/master@{#599034}
[modify] https://crrev.com/f474595943481cff06bb6fc23ce5f1464c39b515/chrome/browser/sessions/session_restore_browsertest_chromeos.cc
[modify] https://crrev.com/f474595943481cff06bb6fc23ce5f1464c39b515/chrome/browser/ui/browser_tabrestore.cc
[modify] https://crrev.com/f474595943481cff06bb6fc23ce5f1464c39b515/ui/views/cocoa/bridged_native_widget_host_impl.mm
[modify] https://crrev.com/f474595943481cff06bb6fc23ce5f1464c39b515/ui/views/widget/native_widget_mac.mm

The following revision refers to this bug: 
https://chromium.googlesource.com/chromium/src.git/+/f474595943481cff06bb6fc23ce5f1464c39b515

Commit: f474595943481cff06bb6fc23ce5f1464c39b515
Author: ellyjones@chromium.org
Commiter: ellyjones@chromium.org
Date: 2018-10-22 12:56:12 +0000 UTC

mac: fix restoring minimized windows

This change:
1) Has BridgedNativeWidgetHostImpl notify the owning Widget when it becomes
   minimized
2) Has session restore not activate minimized browser windows when selecting
   a restored tab
3) Has session restore not show a newly created browser window if it's
   minimized

restore save; without this change, the widget will not get saved as minimized.
window. On Mac, showing/activating a window implies de-minimizing it, so this
is required to avoid de-minimizing saved minimized windows, but I think it is
necessary on other platforms as well.

Test steps:
1) Start Chromium
2) Create a second browser window (cmd-n) and minimize it
3) In the first window, chrome://restart

Before this change, both browser windows appear after restart; after this
change, the first window appears and the second stays minimized.

Note that there is a graphical glitch when first restoring a window that is
minimized this way: the window paints as blank for a few frames while running
the deminiaturize animation.

Bug:  888218 
Change-Id: I8ac121408336a7d6aeedd2b27cd2c9c9d20a18f2
Reviewed-on: https://chromium-review.googlesource.com/c/1268396
Reviewed-by: Scott Violet <sky@chromium.org>
Commit-Queue: Elly Fong-Jones <ellyjones@chromium.org>
Cr-Original-Commit-Position: refs/heads/master@{#599961}(cherry picked from commit 129abeac557646a4c99fdc9f27b00989b7fd36c1)
Reviewed-on: https://chromium-review.googlesource.com/c/1293551
Reviewed-by: Elly Fong-Jones <ellyjones@chromium.org>
Cr-Commit-Position: refs/branch-heads/3578@{#203}
Cr-Branched-From: 4226ddf99103e493d7afb23a4c7902ee496108b6-refs/heads/master@{#599034}