[CrOS PhoneHub] Update dismissed notification on multidevice-internals.

When user dismisses a notification, the background of the notification
form at chrome://multidevice-internals will turn red, and there
will be a string that indicates the notification has been dismissed.
The Update button will also become disabled.

https://screenshot.googleplex.com/5u2nyeJWpUXgFZd

Bug: 1106937
Change-Id: Icc5e933e009c492ca0ee363f28c80e5cf798c3e8
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2414910
Commit-Queue: Regan Hsu <hsuregan@chromium.org>
Reviewed-by: Kyle Horimoto <khorimoto@chromium.org>
Cr-Commit-Position: refs/heads/master@{#807706}