Revert "ash: Keep active window uncovered on display change"

This reverts commit 92ecc62f74072bd8bad6c3401130c3fb476ba5d1.

Reason for revert: suspect ash_unittests failure on Linux Chromium OS ASan LSan Tests
https://ci.chromium.org/p/chromium/builders/ci/Linux%20Chromium%20OS%20ASan%20LSan%20Tests%20%281%29/32865
ExtendedDesktopTest.KeyEventsOnLockScreen
OverviewSessionTest.RemoveDisplay
OverviewSessionTest.RemoveDisplayWithAnimation
PersistentWindowControllerTest.DisconnectDisplay
PersistentWindowControllerTest.MixedMirrorMode
PersistentWindowControllerTest.NormalMirrorMode
PersistentWindowControllerTest.ReconnectOnLockScreen
PersistentWindowControllerTest.RecordNumOfWindowsRestored
PersistentWindowControllerTest.ThreeDisplays
PersistentWindowControllerTest.WindowMovedByAccel
...

https://logs.chromium.org/logs/chromium/buildbucket/cr-buildbucket.appspot.com/8915703982173055536/+/steps/ash_unittests/0/logs/Deterministic_failure:_ExtendedDesktopTest.KeyEventsOnLockScreen__status_CRASH_/0
==31193==ERROR: AddressSanitizer: container-overflow on address 0x6020001da810 at pc 0x55d92be6ea70 bp 0x7ffe03af0a30 sp 0x7ffe03af0a28
READ of size 8 at 0x6020001da810 thread T0
    #0 0x55d92be6ea6f in ReparentAllWindows ./../../ash/root_window_controller.cc:256:41
    #1 0x55d92be6ea6f in ash::RootWindowController::MoveWindowsTo(aura::Window*) ./../../ash/root_window_controller.cc:622:0
    #2 0x55d92bc99cf5 in ash::WindowTreeHostManager::DeleteHost(ash::AshWindowTreeHost*) ./../../ash/display/window_tree_host_manager.cc:563:15

Original change's description:
> ash: Keep active window uncovered on display change
> 
> - FocusActivationStore uses ActivateWindow(nullptr) for deactivating
>   to avoid an arbitrary window covering the active window before
>   Restore().
> - RootWindowController puts the moved windows under existing ones
>   on display change.
> 
> Bug: 945754
> Change-Id: I3cacfd3427b8c98c9ce9dd2da05977120c1c1d65
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1574824
> Reviewed-by: Mitsuru Oshima <oshima@chromium.org>
> Commit-Queue: Xiyuan Xia <xiyuan@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#652678}

TBR=xiyuan@chromium.org,oshima@chromium.org

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

Bug: 945754
Change-Id: Ibf3b8cb823388837f6b3d3052e8258b78fd9a9b7
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1577223
Reviewed-by: Takashi Sakamoto <tasak@google.com>
Commit-Queue: Takashi Sakamoto <tasak@google.com>
Cr-Commit-Position: refs/heads/master@{#652818}
4 files changed