IndexedDB: Defer delete calls when there is a running upgrade

third_party/WebKit/LayoutTests/storage/indexeddb/resources/testharness-helpers.js

 function indexeddb_test(upgrade_func, body_func, description) {
     async_test(function(t) {
         var dbName = 'db' + self.location.pathname + '-' + description;
         var delete_request = indexedDB.deleteDatabase(dbName);
         delete_request.onerror = t.unreached_func('deleteDatabase should not fail');
         delete_request.onsuccess = t.step_func(function(e) {
             var open_request = indexedDB.open(dbName);
             open_request.onerror = t.unreached_func('open should not fail');
             open_request.onupgradeneeded = t.step_func(function(e) {
                 upgrade_func(t, open_request.result);
             });
             open_request.onsuccess = t.step_func(function(e) {
                 body_func(t, open_request.result);
             });
         });
     }, description);
 }
 
 function assert_key_equals(a, b, message) {
     assert_equals(indexedDB.cmp(a, b), 0, message);
 }
+
+// Call with a Test and an array of expected results in order. Returns
+// a function; call the function when a result arrives and when the
+// expected number appear the order will be asserted and test
+// completed.
+function expect(t, expected) {
+    var results = [];
+    return result => {
+        results.push(result);
+        if (results.length === expected.length) {
+            assert_array_equals(results, expected);
+            t.done();
+        }
+    };
+}