To do this, we should use ImageSkiaOperations::CreateIconWithBadge().

This function takes two ImageSkias: the primary and the badge.
PRIMARY - Use ash::network_icon::SignalStrengthImageSource like we already have been (see [2]).
BADGE - Create a new image. We'll need an asset from UX.

[1] https://cs.chromium.org/chromium/src/ui/gfx/image/image_skia_operations.h?q=CreateIconWithBadge
[2] https://cs.chromium.org/chromium/src/chrome/browser/chromeos/net/tether_notification_presenter.cc?q=SignalStrengthImageSource

Here are the assets from UX.

Deleted: download_error_2x.png 2.2 KB

	download_error_2x.png 2.2 KB View Download

Deleted: download_error_1x.png 987 bytes

	download_error_1x.png 987 bytes View Download

Deleted: download_error_2x.svg 964 bytes

download_error_2x.svg 964 bytes Download

Deleted: download_error_1x.svg 940 bytes

download_error_1x.svg 940 bytes Download

Here are the icons. Please let me know if these work.

Deleted: alert-2x.svg 362 bytes

alert-2x.svg 362 bytes Download

Deleted: alert-1x.svg 362 bytes

alert-1x.svg 362 bytes Download

Hey Elizabeth - there is actually already a warning badge used in other notifications, so I think it might be preferable to use the same one. However, it has a rounded red square instead of a circle. What do you think about how this looks?

Deleted: Screenshot 2017-08-02 at 5.12.38 PM.png 1.4 MB

	Screenshot 2017-08-02 at 5.12.38 PM.png 1.4 MB View Download

Most recent icons attached.

Deleted: tethering-error_1x.svg 583 bytes

tethering-error_1x.svg 583 bytes Download

Deleted: tethering-error_2x.svg 567 bytes

tethering-error_2x.svg 567 bytes Download

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/e796860c26cccd41d254412ec41693e3dbf0ac9e

commit e796860c26cccd41d254412ec41693e3dbf0ac9e
Author: Kyle Horimoto <khorimoto@google.com>
Date: Thu Aug 10 23:39:40 2017

[CrOS Tether] Add warning badge to connection failed notification.

Previously, a "cellular icon" image was shown, but this was misleading
since it did not imply any problems. Now, there is a red (!) badge in
the corner of the image.

Bug:  747584 , 672263
Change-Id: I7a57eda165d2f93aaabfa42c553fd903acc81ffb
Reviewed-on: https://chromium-review.googlesource.com/598746
Commit-Queue: Kyle Horimoto <khorimoto@chromium.org>
Reviewed-by: Evan Stade <estade@chromium.org>
Reviewed-by: James Cook <jamescook@chromium.org>
Cr-Commit-Position: refs/heads/master@{#493599}
[modify] https://crrev.com/e796860c26cccd41d254412ec41693e3dbf0ac9e/chrome/app/vector_icons/BUILD.gn
[add] https://crrev.com/e796860c26cccd41d254412ec41693e3dbf0ac9e/chrome/app/vector_icons/warning_badge_circle.1x.icon
[add] https://crrev.com/e796860c26cccd41d254412ec41693e3dbf0ac9e/chrome/app/vector_icons/warning_badge_circle.icon
[modify] https://crrev.com/e796860c26cccd41d254412ec41693e3dbf0ac9e/chrome/browser/chromeos/net/tether_notification_presenter.cc

Approving merge to M61 Chrome OS.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/a89330c78a2807074146f134e85944784f82d3d9

commit a89330c78a2807074146f134e85944784f82d3d9
Author: Kyle Horimoto <khorimoto@google.com>
Date: Fri Aug 11 18:01:53 2017

[CrOS Tether] Add warning badge to connection failed notification.

Previously, a "cellular icon" image was shown, but this was misleading
since it did not imply any problems. Now, there is a red (!) badge in
the corner of the image.

TBR=khorimoto@google.com

(cherry picked from commit e796860c26cccd41d254412ec41693e3dbf0ac9e)

Bug:  747584 , 672263
Change-Id: I7a57eda165d2f93aaabfa42c553fd903acc81ffb
Reviewed-on: https://chromium-review.googlesource.com/598746
Commit-Queue: Kyle Horimoto <khorimoto@chromium.org>
Reviewed-by: Evan Stade <estade@chromium.org>
Reviewed-by: James Cook <jamescook@chromium.org>
Cr-Original-Commit-Position: refs/heads/master@{#493599}
Reviewed-on: https://chromium-review.googlesource.com/612483
Reviewed-by: Kyle Horimoto <khorimoto@chromium.org>
Cr-Commit-Position: refs/branch-heads/3163@{#494}
Cr-Branched-From: ff259bab28b35d242e10186cd63af7ed404fae0d-refs/heads/master@{#488528}
[modify] https://crrev.com/a89330c78a2807074146f134e85944784f82d3d9/chrome/app/vector_icons/BUILD.gn
[add] https://crrev.com/a89330c78a2807074146f134e85944784f82d3d9/chrome/app/vector_icons/warning_badge_circle.1x.icon
[add] https://crrev.com/a89330c78a2807074146f134e85944784f82d3d9/chrome/app/vector_icons/warning_badge_circle.icon
[modify] https://crrev.com/a89330c78a2807074146f134e85944784f82d3d9/chrome/browser/chromeos/net/tether_notification_presenter.cc