Introduce ServiceWorkerHandle for tracking WebServiceWorkerImpl reference

content/browser/service_worker/service_worker_storage.cc

Index: content/browser/service_worker/service_worker_storage.cc
diff --git a/content/browser/service_worker/service_worker_storage.cc b/content/browser/service_worker/service_worker_storage.cc
index a5f88bb91892aa5783bf0f7fdf08046cb77ce7ef..2ef977f6b63bfda26cdf61aaeee45f15026339aa 100644
--- a/content/browser/service_worker/service_worker_storage.cc
+++ b/content/browser/service_worker/service_worker_storage.cc
@@ -36,14 +36,6 @@ ServiceWorkerStorage::ServiceWorkerStorage(
 }
 
 ServiceWorkerStorage::~ServiceWorkerStorage() {
-  // TODO(michaeln): fix the onwership model such that workers can get shutdown
-  // prior to browser close time.
-  for (PatternToRegistrationMap::const_iterator iter =
-           registration_by_pattern_.begin();
-       iter != registration_by_pattern_.end();
-       ++iter) {
-    iter->second->Shutdown();
-  }
   registration_by_pattern_.clear();
 }