Service Worker: Change last update check location and HTTP cache bypass rule (1/2)

Service Worker: Change last update check location and HTTP cache bypass rule (1/2)

As per the last f2f and the follow-up discussion, the registration's last update
check time should be updated only when the script load request actually accessed
network and received response without a network error. The time stamp should be
updated regardless of whether the installation of the fetched resource succeeds
or fails.

This patch involves the following behavior changes:

1. Before: The last update check time was not updated when the installation of
   the fetched resouce fails.
   After: The last update check time is updated regardless of the result of the
   installation.
2. Before: registration.update() always bypassed HTTP cache.
   After: registration.update() no longer forces bypassing the HTTP cache but
   bypasses it only when 24 hours have passed since the last update check, as
   per spec.

Spec: https://github.com/slightlyoff/ServiceWorker/commit/569863f3acd0f5d79beab9d8c63210b8286ee507
Spec discussion: https://github.com/slightlyoff/ServiceWorker/issues/514#issuecomment-135641718

Companion CL (Chromium): https://codereview.chromium.org/1283273002/

BUG=520068

[jungkees, 2015-08-12 16:10:48]

jungkee.song@samsung.com changed reviewers:
+ jinho.bang@samsung.com, l.gombos@samsung.com

[jungkees, 2015-08-12 16:26:27]

PTAL.

[zino, 2015-08-17 11:38:27]

peer review looks good to me

[jungkees, 2015-08-17 11:55:25]

jungkee.song@samsung.com changed reviewers:
+ falken@chromium.org, kinuko@chromium.org, michaeln@chromium.org,
nhiroki@chromium.org, tkent@chromium.org

[jungkees, 2015-08-17 12:00:12]

It has been reviewed from the spec perspective too:
https://github.com/slightlyoff/ServiceWorker/issues/514#issuecomment-130664373.

OWNERs, PTAL.

[nhiroki, 2015-08-19 07:10:23]

lgtm

[falken, 2015-09-10 02:09:39]

This looks good, but the "landing plan" is a bit overkill for this set of CLs.
Also, generally BUG= comes after all prose, so landing plan would be better
before it.

As I wrote in the previous CL, it'd be nice for the description to be more
explicit about the behavior change.

[jungkees, 2015-09-10 15:01:01]

I updated the CL description with the behavior changes and removed the landing
plan part which seems obvious.

[jungkees, 2015-10-06 02:04:55]

Closing this CL in favor of:
https://codereview.chromium.org/1380323002/ (Landed)
https://codereview.chromium.org/1381153004/ (WIP)