Added quota client for serviceworker. Enables 'clear past <time> data'.

content/browser/service_worker/service_worker_version.cc

Index: content/browser/service_worker/service_worker_version.cc
diff --git a/content/browser/service_worker/service_worker_version.cc b/content/browser/service_worker/service_worker_version.cc
index 88d8e482705452cf45e45419d774a190f9c6ecd7..2bb622b2f37326eeb42d24d94efa767b6b04c6ee 100644
--- a/content/browser/service_worker/service_worker_version.cc
+++ b/content/browser/service_worker/service_worker_version.cc
@@ -101,6 +101,7 @@ ServiceWorkerVersion::ServiceWorkerVersion(
       context_(context),
       script_cache_map_(this, context),
       is_doomed_(false),
+      creation_time_(base::Time::Now()),

[michaeln, 2014/10/08 23:09:16]

oh, i thought this would mean when version was created in storage?

What meta data do we want to expose around dates/times/sizes? Looks like that
should be reflected in ServiceWorkerRegistrationInfo and
ServiceWorkerVersionInfo and also in ServiceWorkerUsageInfo for the public api.

At the level of the public api, does this make sense?
 create_date()  // when first registered?
 modification_date() // when last updated?
 last_access_date()  // when last used in some capacity?
 size()  // byte cound of script resources saved to disk?

[dmurph, 2014/10/11 00:02:26]

Mind if I do this in a next patch?

       weak_factory_(this) {
   DCHECK(context_);
   DCHECK(registration);