service worker: Record time respondWith() is settled

Motivations behind this change are:
- To track time spent executing fetch event handers
- To track IPC delay for navigation case (renderer -> browser).
- To track thread hopping delay for subresource case
  (renderer SW thread -> renderer background thread).

Cq-Include-Trybots: luci.chromium.try:linux_mojo
Bug: 877972
Change-Id: I1ea2e17e3270c9f79e6b5104885562b96ac497b0
Reviewed-on: https://chromium-review.googlesource.com/1242579
Reviewed-by: Kinuko Yasuda <kinuko@chromium.org>
Reviewed-by: Matt Falkenhagen <falken@chromium.org>
Commit-Queue: Kenichi Ishibashi <bashi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#595622}
14 files changed