Add path_provider for elinux (#12)

Fixed #9

packages/path_provider/example/lib/main.dart

@@ -0,0 +1,101 @@
+// Copyright 2021 Sony Group Corporation. All rights reserved.
+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'package:flutter/material.dart';
+import 'package:flutter/services.dart';
+import 'package:path_provider_elinux/path_provider_elinux.dart';
+
+void main() {
+  runApp(MyApp());
+}
+
+/// Sample app
+class MyApp extends StatefulWidget {
+  @override
+  _MyAppState createState() => _MyAppState();
+}
+
+class _MyAppState extends State<MyApp> {
+  String? _tempDirectory = 'Unknown';
+  String? _downloadsDirectory = 'Unknown';
+  String? _appSupportDirectory = 'Unknown';
+  String? _documentsDirectory = 'Unknown';
+  final PathProviderELinux _provider = PathProviderELinux();
+
+  @override
+  void initState() {
+    super.initState();
+    initDirectories();
+  }
+
+  // Platform messages are asynchronous, so we initialize in an async method.
+  Future<void> initDirectories() async {
+    String? tempDirectory;
+    String? downloadsDirectory;
+    String? appSupportDirectory;
+    String? documentsDirectory;
+    // Platform messages may fail, so we use a try/catch PlatformException.
+    try {
+      tempDirectory = await _provider.getTemporaryPath();
+    } on PlatformException catch (e, stackTrace) {
+      tempDirectory = 'Failed to get temp directory.';
+      print('$tempDirectory $e $stackTrace');
+    }
+    try {
+      downloadsDirectory = await _provider.getDownloadsPath();
+    } on PlatformException catch (e, stackTrace) {
+      downloadsDirectory = 'Failed to get downloads directory.';
+      print('$downloadsDirectory $e $stackTrace');
+    }
+
+    try {
+      documentsDirectory = await _provider.getApplicationDocumentsPath();
+    } on PlatformException catch (e, stackTrace) {
+      documentsDirectory = 'Failed to get documents directory.';
+      print('$documentsDirectory $e $stackTrace');
+    }
+
+    try {
+      appSupportDirectory = await _provider.getApplicationSupportPath();
+    } on PlatformException catch (e, stackTrace) {
+      appSupportDirectory = 'Failed to get documents directory.';
+      print('$appSupportDirectory $e $stackTrace');
+    }
+    // If the widget was removed from the tree while the asynchronous platform
+    // message was in flight, we want to discard the reply rather than calling
+    // setState to update our non-existent appearance.
+    if (!mounted) {
+      return;
+    }
+
+    setState(() {
+      _tempDirectory = tempDirectory;
+      _downloadsDirectory = downloadsDirectory;
+      _appSupportDirectory = appSupportDirectory;
+      _documentsDirectory = documentsDirectory;
+    });
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    return MaterialApp(
+      home: Scaffold(
+        appBar: AppBar(
+          title: const Text('Path Provider eLinux example app'),
+        ),
+        body: Center(
+          child: Column(
+            children: <Widget>[
+              Text('Temp Directory: $_tempDirectory\n'),
+              Text('Documents Directory: $_documentsDirectory\n'),
+              Text('Downloads Directory: $_downloadsDirectory\n'),
+              Text('Application Support Directory: $_appSupportDirectory\n'),
+            ],
+          ),
+        ),
+      ),
+    );
+  }
+}