ServiceWorker: Migrate the script cache backend from BlockFile to Simple

content/browser/service_worker/service_worker_database.h

Index: content/browser/service_worker/service_worker_database.h
diff --git a/content/browser/service_worker/service_worker_database.h b/content/browser/service_worker/service_worker_database.h
index a43521239015e3c4e90700a83440c843d8167e16..0fc6d6172904a83a09c4e8050311a4e3a9d4398c 100644
--- a/content/browser/service_worker/service_worker_database.h
+++ b/content/browser/service_worker/service_worker_database.h
@@ -92,6 +92,29 @@ class CONTENT_EXPORT ServiceWorkerDatabase {
       int64* next_avail_version_id,
       int64* next_avail_resource_id);
 
+  enum DiskCacheMigrationState {
+    // A diskcache has not been used yet.
+    DISKCACHE_NOT_USED,
+
+    // A diskcache needs to be migrated.
+    DISKCACHE_NEEDS_TO_MIGRATE,
+
+    // A diskcache was migrated but an old diskcache still exists.
+    DISKCACHE_NEEDS_TO_DELETE_OLD,
+
+    // A diskcache was migrated and an old diskcache was deleted.
+    DISKCACHE_MIGRATED,
+
+    DISKCACHE_UNKNOWN_STATE,
+  };
+
+  // Reads a diskcache migration state from the database.
+  Status ReadDiskCacheMigrationState(DiskCacheMigrationState* state);
+
+  // Writes a diskcache migration state in the database. |state| should be
+  // DISKCACHE_MIGRATED or DISKCACHE_NEEDS_TO_DELETE_OLD.
+  Status WriteDiskCacheMigrationState(DiskCacheMigrationState state);
+
   // Reads origins that have one or more than one registration from the
   // database. Returns OK if they are successfully read or not found.
   // Otherwise, returns an error.
@@ -371,6 +394,7 @@ class CONTENT_EXPORT ServiceWorkerDatabase {
   FRIEND_TEST_ALL_PREFIXES(ServiceWorkerDatabaseTest, OpenDatabase);
   FRIEND_TEST_ALL_PREFIXES(ServiceWorkerDatabaseTest, OpenDatabase_InMemory);
   FRIEND_TEST_ALL_PREFIXES(ServiceWorkerDatabaseTest, DatabaseVersion);
+  FRIEND_TEST_ALL_PREFIXES(ServiceWorkerDatabaseTest, DiskCacheMigrationState);
   FRIEND_TEST_ALL_PREFIXES(ServiceWorkerDatabaseTest, GetNextAvailableIds);
   FRIEND_TEST_ALL_PREFIXES(ServiceWorkerDatabaseTest,
                            Registration_UninitializedDatabase);