Web: Return when database is closed

Author: simolus3

packages/sqlite_async/lib/src/web/database.dart

@@ -26,6 +26,9 @@ class WebDatabase
     closed = true;
   }
 
+  @override
+  Future<void> get closedFuture => _database.closed;
+
   @override
   Future<bool> getAutoCommit() async {
     final response = await _database.customRequest(

packages/sqlite_async/lib/src/web/database/web_sqlite_database.dart

@@ -24,6 +24,9 @@ class SqliteDatabaseImpl
     return _connection.closed;
   }
 
+  @override
+  Future<void> get closedFuture => _connection.closedFuture;
+
   final StreamController<UpdateNotification> updatesController =
       StreamController.broadcast();
 

packages/sqlite_async/lib/web.dart

@@ -32,6 +32,13 @@ typedef WebDatabaseEndpoint = ({
 /// opened database across different JavaScript contexts
 /// (e.g. document windows and workers).
 abstract class WebSqliteConnection implements SqliteConnection {
+  /// Returns a future that completes when this connection is closed.
+  ///
+  /// This usually only happens when calling [close], but on the web
+  /// specifically, it can also happen when a remote context closes a database
+  /// accessed via [connectToEndpoint].
+  Future<void> get closedFuture;
+
   /// Returns a [WebDatabaseEndpoint] - a structure that consists only of types
   /// that can be transferred across a [MessagePort] in JavaScript.
   ///