The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/c27aad6fb31a30db4fb13305b906c7521a28253a

commit c27aad6fb31a30db4fb13305b906c7521a28253a
Author: Tetsui Ohkubo <tetsui@chromium.org>
Date: Fri Sep 01 06:06:02 2017

Fix WebNotificationItem leak in WebNotificationTray.

WebNotificationItem is |owned_by_client|. When WebNotificationTray
destructor is called, they are not freed by views::View and leaks.

This fix is needed for landing https://crrev.com/c/605342 without
asan failure.

TEST=WebNotificationTrayTest.VisibleSmallIcon
(out/asan/ash_unittests)
BUG= 760865 

Change-Id: Id3a2e96df09c8864597c0aa460214d2c543ddd08
Reviewed-on: https://chromium-review.googlesource.com/641820
Commit-Queue: Tetsui Ohkubo <tetsui@chromium.org>
Reviewed-by: James Cook <jamescook@chromium.org>
Cr-Commit-Position: refs/heads/master@{#499141}
[modify] https://crrev.com/c27aad6fb31a30db4fb13305b906c7521a28253a/ash/system/web_notification/web_notification_tray.cc
[modify] https://crrev.com/c27aad6fb31a30db4fb13305b906c7521a28253a/ash/system/web_notification/web_notification_tray.h
[modify] https://crrev.com/c27aad6fb31a30db4fb13305b906c7521a28253a/ash/system/web_notification/web_notification_tray_unittest.cc