The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/0e9331a295cef18b775c6cff6e14901075b0ed2a

commit 0e9331a295cef18b775c6cff6e14901075b0ed2a
Author: Tetsui Ohkubo <tetsui@chromium.org>
Date: Wed Jul 18 04:36:48 2018

Unified: Fix tab focus of notification controls.

Tab focusing to notification control buttons was broken in
UnifiedSystemTray because UnifiedMessageCenterView did not implement the
same OnDidChangeFocus logic as MesageCenterView did.

TEST=manual
BUG= 862506 

Change-Id: Ide2d9e170ecefcc87db2d43b6d8d3b1042492374
Reviewed-on: https://chromium-review.googlesource.com/1132907
Reviewed-by: Yoshiki Iguchi <yoshiki@chromium.org>
Commit-Queue: Tetsui Ohkubo <tetsui@chromium.org>
Cr-Commit-Position: refs/heads/master@{#575940}
[modify] https://crrev.com/0e9331a295cef18b775c6cff6e14901075b0ed2a/ash/system/unified/unified_message_center_view.cc
[modify] https://crrev.com/0e9331a295cef18b775c6cff6e14901075b0ed2a/ash/system/unified/unified_message_center_view.h
[modify] https://crrev.com/0e9331a295cef18b775c6cff6e14901075b0ed2a/ash/system/unified/unified_system_tray_bubble.cc
[modify] https://crrev.com/0e9331a295cef18b775c6cff6e14901075b0ed2a/ash/system/unified/unified_system_tray_view.cc
[modify] https://crrev.com/0e9331a295cef18b775c6cff6e14901075b0ed2a/ash/system/unified/unified_system_tray_view.h

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/db9054a59d3d843fd5bdb2389845bfb98600070a

commit db9054a59d3d843fd5bdb2389845bfb98600070a
Author: Tetsui Ohkubo <tetsui@chromium.org>
Date: Wed Aug 01 05:08:28 2018

Unified: Make focus starts from SystemTray part.

This makes focus traversal of UnifiedSystemTray to start from the
SystemTray part. We have notifications above the SystemTray part.
Previously, similar functionality was implemented by TopShortcutsView::
RequestInitFocus(), but it had two downsides:
* It did not make use of ShouldEnableExtraKeyboardAccessibility(), so
  usability with ChromeVox was degraded.
* It did not edit focus traversal order, so the SystemTray part caught
  focus on open only when the tray was opened by Alt-Shift-S. When a
  user opened the tray by mouse and the pressed Tab, notifications
  caught the focus.

TEST=manual
BUG= 862506 

Change-Id: I4fede4f015980c735eedd28f1d05fc19fbded616
Reviewed-on: https://chromium-review.googlesource.com/1156193
Reviewed-by: Yoshiki Iguchi <yoshiki@chromium.org>
Commit-Queue: Tetsui Ohkubo <tetsui@chromium.org>
Cr-Commit-Position: refs/heads/master@{#579706}
[modify] https://crrev.com/db9054a59d3d843fd5bdb2389845bfb98600070a/ash/system/unified/top_shortcuts_view.cc
[modify] https://crrev.com/db9054a59d3d843fd5bdb2389845bfb98600070a/ash/system/unified/top_shortcuts_view.h
[modify] https://crrev.com/db9054a59d3d843fd5bdb2389845bfb98600070a/ash/system/unified/unified_system_tray.cc
[modify] https://crrev.com/db9054a59d3d843fd5bdb2389845bfb98600070a/ash/system/unified/unified_system_tray.h
[modify] https://crrev.com/db9054a59d3d843fd5bdb2389845bfb98600070a/ash/system/unified/unified_system_tray_bubble.cc
[modify] https://crrev.com/db9054a59d3d843fd5bdb2389845bfb98600070a/ash/system/unified/unified_system_tray_bubble.h
[modify] https://crrev.com/db9054a59d3d843fd5bdb2389845bfb98600070a/ash/system/unified/unified_system_tray_controller.cc
[modify] https://crrev.com/db9054a59d3d843fd5bdb2389845bfb98600070a/ash/system/unified/unified_system_tray_view.cc
[modify] https://crrev.com/db9054a59d3d843fd5bdb2389845bfb98600070a/ash/system/unified/unified_system_tray_view.h