ServiceWorker: Migrate the script cache backend from BlockFile to Simple

content/browser/service_worker/service_worker_metrics.h

Index: content/browser/service_worker/service_worker_metrics.h
diff --git a/content/browser/service_worker/service_worker_metrics.h b/content/browser/service_worker/service_worker_metrics.h
index 400cd7eb7d46e5be81d6d77d3dd77815cb63aab5..8af350092b5482175ae1f7aba58035d181926cac 100644
--- a/content/browser/service_worker/service_worker_metrics.h
+++ b/content/browser/service_worker/service_worker_metrics.h
@@ -28,6 +28,13 @@ class ServiceWorkerMetrics {
     NUM_WRITE_RESPONSE_RESULT_TYPES,
   };
 
+  enum DiskCacheMigrationResult {
+    MIGRATION_OK,
+    MIGRATION_NOT_NECESSARY,
+    MIGRATION_ERROR_FAILED,
+    NUM_MIGRATION_RESULT_TYPES,
+  };
+
   enum DeleteAndStartOverResult {
     DELETE_OK,
     DELETE_DATABASE_ERROR,
@@ -48,6 +55,7 @@ class ServiceWorkerMetrics {
 
   // Used for ServiceWorkerStorage.
   static void RecordDeleteAndStartOverResult(DeleteAndStartOverResult result);
+  static void RecordDiskCacheMigrationResult(DiskCacheMigrationResult result);
 
   // Counts the number of page loads controlled by a Service Worker.
   static void CountControlledPageLoad(const GURL& url);