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This is a reland of 16ab50cc
https://chromium-review.googlesource.com/c/chromium/src/+/1184724
The original change was once reverted as it failed on
linux_chromium_chromeos_asan_rel_ng.

Original change's description:
> Add a container view of MessageView to be used for swipe control.
>
> This change adds a new container view between MessageListView and
> MessageView. The new view is intended to host buttons views for swipe
> control.
> This change also returns slided notifications when another notification
> swipe is started, so as to ensure only one swipe control can be opened.
>
> Bug: 840497
> Change-Id: Ica92933a8d3f5d92caa43a5c926252681873ede1
> Reviewed-on: https://chromium-review.googlesource.com/1184724
> Reviewed-by: Yoshiki Iguchi <yoshiki@chromium.org>
> Commit-Queue: Tatsuhisa Yamaguchi <yamaguchi@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#586198}

Bug: 840497,877983
Test: ash_unittests --gtest_filter=MessageCenterViewTest.*:MessageListViewTest.*:ArcNotificationContentViewTest.*
Change-Id: I0c53b727ab317364224894ed8e0853ae10125337
Reviewed-on: https://chromium-review.googlesource.com/1192468Reviewed-by: Stefan Kuhne <skuhne@chromium.org>
Reviewed-by: Evan Stade <estade@chromium.org>
Reviewed-by: Tetsui Ohkubo <tetsui@chromium.org>
Commit-Queue: Tatsuhisa Yamaguchi <yamaguchi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#587114}