Add showTrigger to NotificationOptions.

Bug: 891339
Change-Id: I6d1df509fd7725da90f78c3063cedec9a5479189
Reviewed-on: https://chromium-review.googlesource.com/c/1470235
Commit-Queue: Richard Knoll <knollr@chromium.org>
Reviewed-by: Kinuko Yasuda <kinuko@chromium.org>
Reviewed-by: Peter Beverloo <peter@chromium.org>
Cr-Commit-Position: refs/heads/master@{#636036}
14 files changed