The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/ccb444028112108d32f945c03f1cb16ac0b27b7c

commit ccb444028112108d32f945c03f1cb16ac0b27b7c
Author: Istiaque Ahmed <lazyboy@chromium.org>
Date: Tue Jun 19 02:11:12 2018

Beginnings of SW based background page.

Add manifest key ("service_worker_script") to specify a script
for SW based background page.
Registers the provided script as a worker.
Add extension registry observers to observe the begin/finish of the
SW registration.
Change ServiceWorkerTaskQueue to support queueing tasks. Queueing is
done if the SW registration is pending.

Add a browser_test to load such extension, that doesn't use any
background page.

Doc: https://goo.gl/j4ca5d
Bug: 853378, 850792, 850786
Change-Id: I11c0bdbbbdb6e2ca1e7423330ebd455bdd45fb11
Reviewed-on: https://chromium-review.googlesource.com/1088162
Commit-Queue: Istiaque Ahmed <lazyboy@chromium.org>
Reviewed-by: Matt Falkenhagen <falken@chromium.org>
Reviewed-by: Devlin <rdevlin.cronin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#568300}
[modify] https://crrev.com/ccb444028112108d32f945c03f1cb16ac0b27b7c/chrome/browser/extensions/service_worker_apitest.cc
[modify] https://crrev.com/ccb444028112108d32f945c03f1cb16ac0b27b7c/chrome/common/extensions/manifest_tests/extension_manifests_background_unittest.cc
[add] https://crrev.com/ccb444028112108d32f945c03f1cb16ac0b27b7c/chrome/test/data/extensions/api_test/service_worker/worker_based_background/basic/manifest.json
[add] https://crrev.com/ccb444028112108d32f945c03f1cb16ac0b27b7c/chrome/test/data/extensions/api_test/service_worker/worker_based_background/basic/service_worker_background.js
[add] https://crrev.com/ccb444028112108d32f945c03f1cb16ac0b27b7c/chrome/test/data/extensions/manifest_tests/service_worker_based_background.json
[modify] https://crrev.com/ccb444028112108d32f945c03f1cb16ac0b27b7c/extensions/browser/extension_registrar.cc
[modify] https://crrev.com/ccb444028112108d32f945c03f1cb16ac0b27b7c/extensions/browser/process_manager.cc
[modify] https://crrev.com/ccb444028112108d32f945c03f1cb16ac0b27b7c/extensions/browser/service_worker_task_queue.cc
[modify] https://crrev.com/ccb444028112108d32f945c03f1cb16ac0b27b7c/extensions/browser/service_worker_task_queue.h
[modify] https://crrev.com/ccb444028112108d32f945c03f1cb16ac0b27b7c/extensions/browser/service_worker_task_queue_factory.cc
[modify] https://crrev.com/ccb444028112108d32f945c03f1cb16ac0b27b7c/extensions/common/api/_manifest_features.json
[modify] https://crrev.com/ccb444028112108d32f945c03f1cb16ac0b27b7c/extensions/common/manifest_constants.cc
[modify] https://crrev.com/ccb444028112108d32f945c03f1cb16ac0b27b7c/extensions/common/manifest_constants.h
[modify] https://crrev.com/ccb444028112108d32f945c03f1cb16ac0b27b7c/extensions/common/manifest_handlers/background_info.cc
[modify] https://crrev.com/ccb444028112108d32f945c03f1cb16ac0b27b7c/extensions/common/manifest_handlers/background_info.h