Make sure saveTo returns a Future (flutter#3363)

Author: mvanbeusekom

packages/cross_file/CHANGELOG.md

@@ -1,3 +1,5 @@
+
+
 ## 0.1.0+1
 
 - Update Flutter SDK constraint.

packages/cross_file/lib/src/types/base.dart

@@ -18,7 +18,7 @@ abstract class XFileBase {
   XFileBase(String path);
 
   /// Save the CrossFile at the indicated file path.
-  void saveTo(String path) async {
+  Future<void> saveTo(String path) {
     throw UnimplementedError('saveTo has not been implemented.');
   }
 

packages/cross_file/lib/src/types/html.dart

@@ -108,7 +108,7 @@ class XFile extends XFileBase {
 
   /// Saves the data of this CrossFile at the location indicated by path.
   /// For the web implementation, the path variable is ignored.
-  void saveTo(String path) async {
+  Future<void> saveTo(String path) async {
     // Create a DOM container where we can host the anchor.
     _target = ensureInitialized('__x_file_dom_element');
 

packages/cross_file/lib/src/types/io.dart

@@ -57,7 +57,7 @@ class XFile extends XFileBase {
   }
 
   @override
-  void saveTo(String path) async {
+  Future<void> saveTo(String path) async {
     File fileToSave = File(path);
     await fileToSave.writeAsBytes(_bytes ?? (await readAsBytes()));
     await fileToSave.create();

packages/cross_file/pubspec.yaml

@@ -1,6 +1,7 @@
 name: cross_file
 description: An abstraction to allow working with files across multiple platforms.
 homepage: https://github.com/flutter/plugins/tree/master/packages/cross_file
+
 version: 0.1.0+1
 
 dependencies: