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}
3 files changed