Fix data not being persisted after terminating Worker thread (#1877)

ext/js/data/database.js

@@ -198,6 +198,16 @@ class Database {
         });
     }
 
+    persistData(objectStoreName) {
+        return new Promise((resolve, reject) => {
+            const transaction = this.transaction([objectStoreName], 'readonly');
+            const objectStore = transaction.objectStore(objectStoreName);
+            const cursor = objectStore.openCursor();
+            cursor.onerror = (e) => reject(e.target.error);
+            cursor.onsuccess = () => resolve();
+        });
+    }
+
     static deleteDatabase(databaseName) {
         return new Promise((resolve, reject) => {
             const request = indexedDB.deleteDatabase(databaseName);

ext/js/language/dictionary-database.js

@@ -317,6 +317,10 @@ class DictionaryDatabase {
         return this._db.bulkAdd(objectStoreName, items, start, count);
     }
 
+    persistData(objectStoreName) {
+        return this._db.persistData(objectStoreName);
+    }
+
     // Private
 
     _findMultiBulk(objectStoreName, indexNames, items, createQuery, predicate, createResult) {

ext/js/language/dictionary-importer.js

@@ -149,6 +149,10 @@ class DictionaryImporter {
                 this._progressData.index += count;
                 this._progress();
             }
+
+            // This function is required in order to make the added data persist after the worker is terminated.
+            // https://bugs.chromium.org/p/chromium/issues/detail?id=1237686
+            await dictionaryDatabase.persistData(objectStoreName);
         };
 
         await bulkAdd('terms', termList);