This had been fixed for the old message center by the following CL: https://chromium.googlesource.com/chromium/src.git/+/1765a2a95967802c4ad45f3129deeaaec957f66d

But it's happened with the new unified system tray, since the behavior is changed on showing the message center:
- Old message center: reuse MessageView instance
- New unified system tray: destroy MessageView instance and recreate it

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/0be0e558ab0262fbfe4a4b27ee41c0b7c89418dc

commit 0be0e558ab0262fbfe4a4b27ee41c0b7c89418dc
Author: yoshiki iguchi <yoshiki@chromium.org>
Date: Wed Sep 12 07:32:11 2018

Destroy a popup view before the message center opens

This CL adds an option to remove the animation on removing a popup.
As the result of that, the popup view can be destroyed before the message
center opens.

Previously, a popup view was not closed at the time of opening the message
center and the 2 same views existed at the same time briefly. And it
had caused a blank notifications in the message center (see the issue).
This CL fixes this issue.

Bug:  882421 
Change-Id: I5c1d4891135b8f32cb9d7b99a9d6a3c677794446
Reviewed-on: https://chromium-review.googlesource.com/1216067
Reviewed-by: Tetsui Ohkubo <tetsui@chromium.org>
Commit-Queue: Yoshiki Iguchi <yoshiki@chromium.org>
Cr-Commit-Position: refs/heads/master@{#590614}
[modify] https://crrev.com/0be0e558ab0262fbfe4a4b27ee41c0b7c89418dc/ash/message_center/message_center_ui_controller.cc
[modify] https://crrev.com/0be0e558ab0262fbfe4a4b27ee41c0b7c89418dc/ash/message_center/message_center_ui_controller.h
[modify] https://crrev.com/0be0e558ab0262fbfe4a4b27ee41c0b7c89418dc/ash/message_center/message_center_ui_controller_unittest.cc
[modify] https://crrev.com/0be0e558ab0262fbfe4a4b27ee41c0b7c89418dc/ash/message_center/message_center_ui_delegate.h
[modify] https://crrev.com/0be0e558ab0262fbfe4a4b27ee41c0b7c89418dc/ash/system/message_center/notification_tray.cc
[modify] https://crrev.com/0be0e558ab0262fbfe4a4b27ee41c0b7c89418dc/ash/system/message_center/notification_tray.h
[modify] https://crrev.com/0be0e558ab0262fbfe4a4b27ee41c0b7c89418dc/ash/system/unified/unified_system_tray.cc
[modify] https://crrev.com/0be0e558ab0262fbfe4a4b27ee41c0b7c89418dc/chrome/browser/ui/views/message_center/popups_only_ui_delegate.cc
[modify] https://crrev.com/0be0e558ab0262fbfe4a4b27ee41c0b7c89418dc/ui/message_center/views/message_popup_collection.cc
[modify] https://crrev.com/0be0e558ab0262fbfe4a4b27ee41c0b7c89418dc/ui/message_center/views/message_popup_collection.h
[modify] https://crrev.com/0be0e558ab0262fbfe4a4b27ee41c0b7c89418dc/ui/message_center/views/message_popup_collection_unittest.cc

Approved for M70

This issue has been approved for a merge. Please merge the fix to any appropriate branches as soon as possible!

If all merges have been completed, please remove any remaining Merge-Approved labels from this issue.

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The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/c839ced23655d9cc657fd149b7bd9146aaa2dccc

commit c839ced23655d9cc657fd149b7bd9146aaa2dccc
Author: yoshiki iguchi <yoshiki@chromium.org>
Date: Wed Sep 19 07:28:06 2018

Destroy a popup view before the message center opens

This CL adds an option to remove the animation on removing a popup.
As the result of that, the popup view can be destroyed before the message
center opens.

Previously, a popup view was not closed at the time of opening the message
center and the 2 same views existed at the same time briefly. And it
had caused a blank notifications in the message center (see the issue).
This CL fixes this issue.

TBR=yoshiki@chromium.org

(cherry picked from commit 0be0e558ab0262fbfe4a4b27ee41c0b7c89418dc)

Bug:  882421 
Change-Id: I5c1d4891135b8f32cb9d7b99a9d6a3c677794446
Reviewed-on: https://chromium-review.googlesource.com/1216067
Reviewed-by: Tetsui Ohkubo <tetsui@chromium.org>
Commit-Queue: Yoshiki Iguchi <yoshiki@chromium.org>
Cr-Original-Commit-Position: refs/heads/master@{#590614}
Reviewed-on: https://chromium-review.googlesource.com/1233334
Reviewed-by: Yoshiki Iguchi <yoshiki@chromium.org>
Cr-Commit-Position: refs/branch-heads/3538@{#523}
Cr-Branched-From: 79f7c91a2b2a2932cd447fa6f865cb6662fa8fa6-refs/heads/master@{#587811}
[modify] https://crrev.com/c839ced23655d9cc657fd149b7bd9146aaa2dccc/ash/message_center/message_center_ui_controller.cc
[modify] https://crrev.com/c839ced23655d9cc657fd149b7bd9146aaa2dccc/ash/message_center/message_center_ui_controller.h
[modify] https://crrev.com/c839ced23655d9cc657fd149b7bd9146aaa2dccc/ash/message_center/message_center_ui_controller_unittest.cc
[modify] https://crrev.com/c839ced23655d9cc657fd149b7bd9146aaa2dccc/ash/message_center/message_center_ui_delegate.h
[modify] https://crrev.com/c839ced23655d9cc657fd149b7bd9146aaa2dccc/ash/system/message_center/notification_tray.cc
[modify] https://crrev.com/c839ced23655d9cc657fd149b7bd9146aaa2dccc/ash/system/message_center/notification_tray.h
[modify] https://crrev.com/c839ced23655d9cc657fd149b7bd9146aaa2dccc/ash/system/unified/unified_system_tray.cc
[modify] https://crrev.com/c839ced23655d9cc657fd149b7bd9146aaa2dccc/chrome/browser/ui/views/message_center/popups_only_ui_delegate.cc
[modify] https://crrev.com/c839ced23655d9cc657fd149b7bd9146aaa2dccc/ui/message_center/views/message_popup_collection.cc
[modify] https://crrev.com/c839ced23655d9cc657fd149b7bd9146aaa2dccc/ui/message_center/views/message_popup_collection.h
[modify] https://crrev.com/c839ced23655d9cc657fd149b7bd9146aaa2dccc/ui/message_center/views/message_popup_collection_unittest.cc