GitLab

Previously, the STOP button would cause the timer to stop ringing. This
was sufficient because we only showed a notification for ringing timers.
Since we will now show notifications for ticking timers, the STOP button
needs to actually remove the associated timer.

This CL:
- Removes the StopRinging API as it is no longer needed, and there is no
  need for it anytime soon (to my knowledge).
- Adds a RemoveAlarmTimer API.
- Updates DeepLinkUtil to reflect changes in possible AlarmTimerActions.
- Updates unittests and creates a new browsertest verifying changes.

Note that this CL adds assistant_timers_browsertest as
assistant_browsertest is growing large. A follow up CL will migrate
existing timer browsertests to the new location.

Also note that this CL removes support for in-Assistant notification
types since it was the sole user of the StopRinging API and there is no
plan to launch the feature following standalone UI deprecation. The
pipeline to support notifications of multiple types has *not* been
removed at this time as it may prove useful later.

Bug: b:149570650
Change-Id: I4cbf0da246237f8402b075ace0f0e1c98348e296
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2132622
Commit-Queue: David Black <dmblack@google.com>
Reviewed-by: Evan Stade <estade@chromium.org>
Reviewed-by: Xiyuan Xia <xiyuan@chromium.org>
Reviewed-by: Daniel Cheng <dcheng@chromium.org>
Reviewed-by: Xiaohui Chen <xiaohuic@chromium.org>
Cr-Commit-Position: refs/heads/master@{#758981}