After 24 hours, bust the browser cache when checking for ServiceWorker updates

content/browser/service_worker/service_worker_registration.h

Index: content/browser/service_worker/service_worker_registration.h
diff --git a/content/browser/service_worker/service_worker_registration.h b/content/browser/service_worker/service_worker_registration.h
index e8e65b37b8860a09cbb34e55168e7ffca12361d6..570c3310ac568fc0b56d8e35c4098cabeb1a153d 100644
--- a/content/browser/service_worker/service_worker_registration.h
+++ b/content/browser/service_worker/service_worker_registration.h
@@ -88,6 +88,10 @@ class CONTENT_EXPORT ServiceWorkerRegistration
   bool is_deleted() const { return is_deleted_; }
   void set_is_deleted() { is_deleted_ = true; }
 
+  // The time of the most recent update check.
+  base::Time last_update_check() const { return last_update_check_; }
+  void set_last_update_check(base::Time last) { last_update_check_ = last; }
+
  private:
   friend class base::RefCounted<ServiceWorkerRegistration>;
 
@@ -117,6 +121,7 @@ class CONTENT_EXPORT ServiceWorkerRegistration
   const int64 registration_id_;
   bool is_deleted_;
   bool should_activate_when_ready_;
+  base::Time last_update_check_;
   scoped_refptr<ServiceWorkerVersion> active_version_;
   scoped_refptr<ServiceWorkerVersion> waiting_version_;
   scoped_refptr<ServiceWorkerVersion> installing_version_;