[file_selector_platform_interface] Migrate to cross_file package (flutter#3286)

Author: mvanbeusekom

packages/file_selector/file_selector_platform_interface/CHANGELOG.md

@@ -1,3 +1,7 @@
+## 1.0.2
+
+* Replace locally defined `XFile` types with the versions from the [cross_file](https://pub.dev/packages/cross_file) package.
+
 ## 1.0.1
 
 * Allow type groups that allow any file.

packages/file_selector/file_selector_platform_interface/lib/src/method_channel/method_channel_file_selector.dart

@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+import 'package:cross_file/cross_file.dart';
 import 'package:flutter/services.dart';
 
 import 'package:file_selector_platform_interface/file_selector_platform_interface.dart';

packages/file_selector/file_selector_platform_interface/lib/src/platform_interface/file_selector_interface.dart

@@ -4,6 +4,7 @@
 
 import 'dart:async';
 
+import 'package:cross_file/cross_file.dart';
 import 'package:file_selector_platform_interface/file_selector_platform_interface.dart';
 import 'package:plugin_platform_interface/plugin_platform_interface.dart';
 

packages/file_selector/file_selector_platform_interface/lib/src/types/types.dart

@@ -1,3 +1,2 @@
-export 'x_file/x_file.dart';
-
+export 'package:cross_file/cross_file.dart';
 export 'x_type_group/x_type_group.dart';