Issue 846235 is tracking the implementation.

📍 Pinpoint job started.
https://pinpoint-dot-chromeperf.appspot.com/job/11c34885240000

📍 Job complete. See results below.
https://pinpoint-dot-chromeperf.appspot.com/job/11c34885240000

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/6e67d953ba38b4172a8bcd1928e49f65e86e8a1b

commit 6e67d953ba38b4172a8bcd1928e49f65e86e8a1b
Author: Makoto Shimazu <shimazu@chromium.org>
Date: Thu Jun 14 09:25:57 2018

ServiceWorker: More traces for events dispatched to service workers

Bug:  852202 , 669772,  806658 
Change-Id: Ife9c41fbe08c1f414bb5459cba29d98d7e1fb892
Reviewed-on: https://chromium-review.googlesource.com/1098650
Commit-Queue: Makoto Shimazu <shimazu@chromium.org>
Reviewed-by: Matt Falkenhagen <falken@chromium.org>
Cr-Commit-Position: refs/heads/master@{#567205}
[modify] https://crrev.com/6e67d953ba38b4172a8bcd1928e49f65e86e8a1b/content/common/service_worker/service_worker_utils.cc
[modify] https://crrev.com/6e67d953ba38b4172a8bcd1928e49f65e86e8a1b/content/common/service_worker/service_worker_utils.h
[modify] https://crrev.com/6e67d953ba38b4172a8bcd1928e49f65e86e8a1b/content/renderer/service_worker/service_worker_context_client.cc
[modify] https://crrev.com/6e67d953ba38b4172a8bcd1928e49f65e86e8a1b/content/renderer/service_worker/web_service_worker_provider_impl.cc

Regarding to the result of pinpoint, I couldn't read any reliable performance insights from there.

I looked at timeToFirstContentfulPaint by splitting into "stories" and "cache_temperatureTag", and FlipKart::hot with NetS13nSW was slightly better but it's in the range of stdev. DevOpera results are in very wide range, so I don't think it's reliable.

So, I think we can conclude that we don't have obvious and significant regressions for now. Let's revisit the performance after starting experiment in wild.

We did local testing and fixed major issues.
 issue 856521 : serving cached meta data
 issue 854902 : avoiding thread hop to the main thread

In the next step, let's see the performance in wild.