ServiceWorker: Print error message when failed to open diskcache

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 9a79263d718d49b94d630fe81914daa1fcee4091..ee64e0cecec86bd01091a37d437b38594db5345f 100644
--- a/content/browser/service_worker/service_worker_storage.cc
+++ b/content/browser/service_worker/service_worker_storage.cc
@@ -694,7 +694,8 @@ ServiceWorkerDiskCache* ServiceWorkerStorage::disk_cache() {
 
 void ServiceWorkerStorage::OnDiskCacheInitialized(int rv) {
   if (rv != net::OK) {
-    LOG(ERROR) << "Failed to open the serviceworker diskcache.";
+    LOG(ERROR) << "Failed to open the serviceworker diskcache: "
+               << net::ErrorToString(rv);
     // TODO(michaeln): DeleteAndStartOver()
     disk_cache_->Disable();
     state_ = DISABLED;