Hmm I believe this is fixed, I was able to repro earlier but I can't as of today.

derat@ - Can you verify?

I'm not set up to easily test this anywhere, but I'm happy to reopen if I continue noticing it in the future. :-)

I don't think that this was ever fixed; it's still trivial to reproduce:

Google Chrome	67.0.3396.99 (Official Build) (64-bit)
Revision	a337fbf3c2ab8ebc6b64b0bfdce73a20e2e2252b-refs/branch-heads/3396@{#790}
Platform	10575.58.0 (Official Build) stable-channel eve

It's quite frustrating -- every time I use the device in tablet mode, the other desktop's windows are resized.

Sammie, when will you be able to look into this? It causes a painful user experience when using multiuser and tablet mode at the same time.

Google Chrome	68.0.3440.118 (Official Build) (64-bit)
Revision	a7ca4397b06108b300bc00c52932eaeae010e662-refs/branch-heads/3440@{#808}
Platform	10718.88.2 (Official Build) stable-channel eve

I can take a look on early next week to see if I can get a fix in, but I havent been able to reproduce it on my current device (68.0.3440.118).

What I did:

1. Sign in to a secondary account while in clamshell and open a browser window on its desktop (maximized browser window by default).
2. Go back to the primary account and enter tablet mode.
3. Rotate the device to portrait orientation.
4. Rotate back to landscape orientation.
5. Go back to laptop mode.
6. Go to secondary account -> browser window is maximized still.

Is there something I misunderstood/missing?

Don't maximize the window on the secondary account. (I'm surprised that this is the default when you're in clamshell mode -- I don't think that that's what I see.)

1. Open non-maximized window on secondary account while in laptop mode. (Window width being greater than display height may be a requirement, but that's the common case anyway.)
2. Go to primary account and enter tablet mode.
3. Rotate to portrait.
4. Rotate back to landscape.
5. Go back to laptop mode.
6. Go to secondary account. Browser window is narrow instead of original size.

Thanks! I should've tried that before asking too soon. I'll take a look Monday.

No problem, and thanks!

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/1287062f782551b52676553d89199811d0da3eb4

commit 1287062f782551b52676553d89199811d0da3eb4
Author: Sammie Quon <sammiequon@google.com>
Date: Wed Sep 19 22:21:52 2018

tablet: Remember secondary users bounds when enter/exit tablet mode.

See bug for more information. TabletModeWindowManager is responsible
for returning the window to its clamshell bounds, but it does not track
window on a secondary user since those windows are not visible. They
still get maximized because TabletModeWindowManager becomes aware of
them when switching users.

This approach adds all windows managed by MultiUserWindowManagerCros
when tablet mode is started.

Test: unit_tests MultiUserWindowManagerChromeOSTest.WindowBoundsAfterTabletMode
Bug:  733639 
Change-Id: I14c5e940fe1337789e987e19d8336f0a06e03735
Reviewed-on: https://chromium-review.googlesource.com/1229178
Reviewed-by: Jonathan Ross <jonross@chromium.org>
Reviewed-by: Dan Erat <derat@chromium.org>
Commit-Queue: Sammie Quon <sammiequon@chromium.org>
Cr-Commit-Position: refs/heads/master@{#592575}
[modify] https://crrev.com/1287062f782551b52676553d89199811d0da3eb4/chrome/browser/ui/ash/multi_user/multi_user_window_manager_chromeos.cc
[modify] https://crrev.com/1287062f782551b52676553d89199811d0da3eb4/chrome/browser/ui/ash/multi_user/multi_user_window_manager_chromeos.h
[modify] https://crrev.com/1287062f782551b52676553d89199811d0da3eb4/chrome/browser/ui/ash/multi_user/multi_user_window_manager_chromeos_unittest.cc