Repro video: https://storage.cloud.google.com/chromiumos-test-logs/bugfiles/cr/833685/IMG_7240.MOV?_ga=2.188457192.-1949964863.1508264737

I'll fix it.

Splitview does not work in multi-profile scenario. For a quick fix, I think we should just end split view mode when the active user changes. amusbach@, can you take a look? (seems you don't have a chromium account yet, assign to your google account first).
 
We may need investigate more how split view should interact in multiprofile scenario in the future if needed.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/3009eaced8125010fa7230d0c84674309eeac552

commit 3009eaced8125010fa7230d0c84674309eeac552
Author: Avery Musbach <amusbach@chromium.org>
Date: Fri Jan 18 23:54:30 2019

splitview: Make split view work as expected with multiprofile.

BEFORE: On switching away from a user session in split view, the split
view divider is seen in the newly activated user session where any
windows are maximized. It looks horribly wrong.
AFTER: The split view state on switching away from a user session is
restored on switching back to it.

Test: manual
Bug:  833685 
Change-Id: If5f1721d9015f59615e212425c2b8f21838572e7
Reviewed-on: https://chromium-review.googlesource.com/c/1389695
Reviewed-by: Xiaoqian Dai <xdai@chromium.org>
Reviewed-by: Dan Erat <derat@chromium.org>
Commit-Queue: Avery Musbach <amusbach@chromium.org>
Cr-Commit-Position: refs/heads/master@{#624363}
[modify] https://crrev.com/3009eaced8125010fa7230d0c84674309eeac552/ash/wm/splitview/split_view_controller.cc
[modify] https://crrev.com/3009eaced8125010fa7230d0c84674309eeac552/ash/wm/splitview/split_view_controller.h
[modify] https://crrev.com/3009eaced8125010fa7230d0c84674309eeac552/ash/wm/tablet_mode/tablet_mode_window_manager.cc

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/0e505c4d47166acfca36b6137fb58962d1450c1c

commit 0e505c4d47166acfca36b6137fb58962d1450c1c
Author: Hiroki Nakagawa <nhiroki@chromium.org>
Date: Mon Jan 21 02:01:47 2019

Revert "splitview: Make split view work as expected with multiprofile."

This reverts commit 3009eaced8125010fa7230d0c84674309eeac552.

Reason for revert:

This CL seems to cause heap-use-after-free failures on...

- Linux Chromium OS ASan LSan Tests
https://ci.chromium.org/p/chromium/builders/luci.chromium.ci/Linux%20Chromium%20OS%20ASan%20LSan%20Tests%20%281%29/31123
- Linux ChromiumOS MSan Tests
https://ci.chromium.org/p/chromium/builders/luci.chromium.ci/Linux%20ChromiumOS%20MSan%20Tests/10815

The failure happens in ash::SplitViewController::~SplitViewController().

Original change's description:
> splitview: Make split view work as expected with multiprofile.
> 
> BEFORE: On switching away from a user session in split view, the split
> view divider is seen in the newly activated user session where any
> windows are maximized. It looks horribly wrong.
> AFTER: The split view state on switching away from a user session is
> restored on switching back to it.
> 
> Test: manual
> Bug:  833685 
> Change-Id: If5f1721d9015f59615e212425c2b8f21838572e7
> Reviewed-on: https://chromium-review.googlesource.com/c/1389695
> Reviewed-by: Xiaoqian Dai <xdai@chromium.org>
> Reviewed-by: Dan Erat <derat@chromium.org>
> Commit-Queue: Avery Musbach <amusbach@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#624363}

TBR=derat@chromium.org,skuhne@chromium.org,xdai@chromium.org,afakhry@chromium.org,amusbach@chromium.org

# Not skipping CQ checks because original CL landed > 1 day ago.

Bug:  833685 
Change-Id: I0e63f17f3dc781074e6a18768bc9fda611caeb7b
Reviewed-on: https://chromium-review.googlesource.com/c/1424621
Reviewed-by: Hiroki Nakagawa <nhiroki@chromium.org>
Commit-Queue: Hiroki Nakagawa <nhiroki@chromium.org>
Cr-Commit-Position: refs/heads/master@{#624507}
[modify] https://crrev.com/0e505c4d47166acfca36b6137fb58962d1450c1c/ash/wm/splitview/split_view_controller.cc
[modify] https://crrev.com/0e505c4d47166acfca36b6137fb58962d1450c1c/ash/wm/splitview/split_view_controller.h
[modify] https://crrev.com/0e505c4d47166acfca36b6137fb58962d1450c1c/ash/wm/tablet_mode/tablet_mode_window_manager.cc

(Chromium sheriff) I reverted the change (see c#8).

Thank you!

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/00335ff32893663f6f8c4642b0cd0ae3a72afa6e

commit 00335ff32893663f6f8c4642b0cd0ae3a72afa6e
Author: Avery Musbach <amusbach@chromium.org>
Date: Tue Jan 22 18:56:01 2019

RELAND - splitview: Make split view work as expected with multiprofile.

BEFORE: On switching away from a user session in split view, the split
view divider is seen in the newly activated user session where any
windows are maximized. It looks horribly wrong.
AFTER: The split view state on switching away from a user session is
restored on switching back to it.

TBR=derat@chromium.org

Test: manual
Bug:  833685 
Change-Id: I6c960f86ed921b15c4330ffeb1e79fbcdc095b0c
Reviewed-on: https://chromium-review.googlesource.com/c/1426922
Reviewed-by: Xiaoqian Dai <xdai@chromium.org>
Commit-Queue: Avery Musbach <amusbach@chromium.org>
Cr-Commit-Position: refs/heads/master@{#624850}
[modify] https://crrev.com/00335ff32893663f6f8c4642b0cd0ae3a72afa6e/ash/wm/splitview/split_view_controller.cc
[modify] https://crrev.com/00335ff32893663f6f8c4642b0cd0ae3a72afa6e/ash/wm/splitview/split_view_controller.h
[modify] https://crrev.com/00335ff32893663f6f8c4642b0cd0ae3a72afa6e/ash/wm/tablet_mode/tablet_mode_window_manager.cc