Register Alarms Timers Manager event listener for timer events.

Bug: b:119116816
Change-Id: I00359bb21a310fb230459d8f651d50a01d45e5fe
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1461505
Commit-Queue: Li Lin <llin@chromium.org>
Reviewed-by: Daniel Cheng <dcheng@chromium.org>
Reviewed-by: Xiaohui Chen <xiaohuic@chromium.org>
Cr-Commit-Position: refs/heads/master@{#645599}
7 files changed