Ugh, not this again :( Both tengs@ and I observed notifications not showing on certain platform versions in the past. I reported it previously at  crbug.com/729179 .

yoshiki@, can you please look over this issue?

The code (mentioned in  Issue 729179 ) seems good for me.

I want to test it locally. How can I test it? What is "an eligible android phone"?

I've created a very simple repro here: https://chromium-review.googlesource.com/c/585354/

The call to NotificationPresenter::NotifyMultiplePotentialHotspotsNearby() is not displaying a notification as it has before. 

To use this repro, simply build/deploy and log in. NotifyMultiplePotentialHotspotsNearby will be called on user login.

As I tried the patch you mentioned in #4 on local samus, a notification with ID = cros_tether_notification_ids.potential_hotspot appears in the message center.

Does this issue happen only on caroline?

Hi yoshiki@,

We seem to only be observing this on caroline, but in the past we saw this same kind of issue on veyron_minnie, sentry, and possibly reef.

Do you have a caroline you can test this repro patch on?

Ryan, as we chatted, could you try to set NotifierId#profile_id?

Yoshiki and I spoke earlier yesterday, and he was extremely helpful, correctly pointing me to the problematic code: https://cs.chromium.org/chromium/src/chrome/browser/ui/ash/multi_user/multi_user_notification_blocker_chromeos.cc?sq=package:chromium&dr=CSs&l=24. Thanks!

This threw us off because the documentation explicitly says that leaving profile_id empty is fine -- but clearly it isn't. Should the documentation be changed, or are we misunderstanding it?

In any case, the fix moving forward for us is actually to register Tether as a system notification, under the constants in ash::system_notifier. CL coming soon. 

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/7e01241fbc87142ee25c049360a20ab3306829a7

commit 7e01241fbc87142ee25c049360a20ab3306829a7
Author: Ryan Hansberry <hansberry@chromium.org>
Date: Wed Aug 02 17:18:48 2017

Add Tether to list of ash system notifiers.

Without being a system notifier, 
MultiUserNotificationBlockerChromeOS::ShouldShowNotification()
returns false, preventing Tether notifications from
displaying. It's appropriate to consider Tether a system 
notifier given that it is baked into the system tray and 
Settings.

Bug:  747639 , 672263
Change-Id: I0f0d9a4ce3da7c62b148af979c611eaca6682053
Reviewed-on: https://chromium-review.googlesource.com/596833
Commit-Queue: Ryan Hansberry <hansberry@chromium.org>
Reviewed-by: Kyle Horimoto <khorimoto@chromium.org>
Reviewed-by: Steven Bennetts <stevenjb@chromium.org>
Reviewed-by: James Cook <jamescook@chromium.org>
Cr-Commit-Position: refs/heads/master@{#491416}
[modify] https://crrev.com/7e01241fbc87142ee25c049360a20ab3306829a7/ash/system/system_notifier.cc
[modify] https://crrev.com/7e01241fbc87142ee25c049360a20ab3306829a7/ash/system/system_notifier.h
[modify] https://crrev.com/7e01241fbc87142ee25c049360a20ab3306829a7/chrome/browser/chromeos/net/DEPS
[modify] https://crrev.com/7e01241fbc87142ee25c049360a20ab3306829a7/chrome/browser/chromeos/net/tether_notification_presenter.cc
[modify] https://crrev.com/7e01241fbc87142ee25c049360a20ab3306829a7/chrome/browser/chromeos/net/tether_notification_presenter.h

I've put up a simple CL for review (https://chromium-review.googlesource.com/c/598499) to try to prevent others from hitting the same gotcha we just did.

 Issue 729179  has been merged into this issue.

Approving merge to M61 Chrome OS.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/10ae173bdf75ce0fc0ae6e54e86c13fa5e8a0b19

commit 10ae173bdf75ce0fc0ae6e54e86c13fa5e8a0b19
Author: Kyle Horimoto <khorimoto@google.com>
Date: Wed Aug 02 23:33:03 2017

Add Tether to list of ash system notifiers.

Without being a system notifier,
MultiUserNotificationBlockerChromeOS::ShouldShowNotification()
returns false, preventing Tether notifications from
displaying. It's appropriate to consider Tether a system
notifier given that it is baked into the system tray and
Settings.

TBR=hansberry@chromium.org

(cherry picked from commit 7e01241fbc87142ee25c049360a20ab3306829a7)

Bug:  747639 , 672263
Change-Id: I0f0d9a4ce3da7c62b148af979c611eaca6682053
Reviewed-on: https://chromium-review.googlesource.com/596833
Commit-Queue: Ryan Hansberry <hansberry@chromium.org>
Reviewed-by: Kyle Horimoto <khorimoto@chromium.org>
Reviewed-by: Steven Bennetts <stevenjb@chromium.org>
Reviewed-by: James Cook <jamescook@chromium.org>
Cr-Original-Commit-Position: refs/heads/master@{#491416}
Reviewed-on: https://chromium-review.googlesource.com/598698
Cr-Commit-Position: refs/branch-heads/3163@{#251}
Cr-Branched-From: ff259bab28b35d242e10186cd63af7ed404fae0d-refs/heads/master@{#488528}
[modify] https://crrev.com/10ae173bdf75ce0fc0ae6e54e86c13fa5e8a0b19/ash/system/system_notifier.cc
[modify] https://crrev.com/10ae173bdf75ce0fc0ae6e54e86c13fa5e8a0b19/ash/system/system_notifier.h
[modify] https://crrev.com/10ae173bdf75ce0fc0ae6e54e86c13fa5e8a0b19/chrome/browser/chromeos/net/DEPS
[modify] https://crrev.com/10ae173bdf75ce0fc0ae6e54e86c13fa5e8a0b19/chrome/browser/chromeos/net/tether_notification_presenter.cc
[modify] https://crrev.com/10ae173bdf75ce0fc0ae6e54e86c13fa5e8a0b19/chrome/browser/chromeos/net/tether_notification_presenter.h