ServiceWorker: Migrate the script cache backend from BlockFile to Simple

content/browser/service_worker/service_worker_metrics.cc

Index: content/browser/service_worker/service_worker_metrics.cc
diff --git a/content/browser/service_worker/service_worker_metrics.cc b/content/browser/service_worker/service_worker_metrics.cc
index c0d882d3901da91410eabf4b8c48ea3ffdae0018..31d16fe1238903139560ae6197500c15306c00da 100644
--- a/content/browser/service_worker/service_worker_metrics.cc
+++ b/content/browser/service_worker/service_worker_metrics.cc
@@ -63,6 +63,12 @@ void ServiceWorkerMetrics::RecordDestroyDatabaseResult(
                             status, ServiceWorkerDatabase::STATUS_ERROR_MAX);
 }
 
+void ServiceWorkerMetrics::RecordDiskCacheMigrationResult(
+    DiskCacheMigrationResult result) {
+  UMA_HISTOGRAM_ENUMERATION("ServiceWorker.Storage.DiskCacheMigrationResult",
+                            result, NUM_MIGRATION_RESULT_TYPES);
+}
+
 void ServiceWorkerMetrics::RecordDeleteAndStartOverResult(
     DeleteAndStartOverResult result) {
   UMA_HISTOGRAM_ENUMERATION("ServiceWorker.Storage.DeleteAndStartOverResult",