Store the service worker script and its imports on first load... kinda

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 77e01c1a470d7b9719000a9c2f73284d7ec5a4e6..82a1146b1ebe35c5120d723b656c9dc3efcd55a0 100644
--- a/content/browser/service_worker/service_worker_version.cc
+++ b/content/browser/service_worker/service_worker_version.cc
@@ -561,4 +561,9 @@ int64 ServiceWorkerVersion::LookupInScriptCache(const GURL& url) {
   return found->second;
 }
 
+void ServiceWorkerVersion::NotifyMainScriptCacheResult(bool success) {
+  FOR_EACH_OBSERVER(Listener, listeners_,
+                    OnMainScriptCacheResult(this, success));
+}
+
 }  // namespace content