adding in elinux files

elinux/runner/flutter_window.h

@@ -0,0 +1,34 @@
+// Copyright 2021 Sony Corporation. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef FLUTTER_WINDOW_
+#define FLUTTER_WINDOW_
+
+#include <flutter/dart_project.h>
+#include <flutter/flutter_view_controller.h>
+
+#include <memory>
+
+class FlutterWindow {
+ public:
+  explicit FlutterWindow(
+      const flutter::FlutterViewController::ViewProperties view_properties,
+      const flutter::DartProject project);
+  ~FlutterWindow() = default;
+
+  // Prevent copying.
+  FlutterWindow(FlutterWindow const&) = delete;
+  FlutterWindow& operator=(FlutterWindow const&) = delete;
+
+  bool OnCreate();
+  void OnDestroy();
+  void Run();
+
+ private:
+  flutter::FlutterViewController::ViewProperties view_properties_;
+  flutter::DartProject project_;
+  std::unique_ptr<flutter::FlutterViewController> flutter_view_controller_;
+};
+
+#endif  // FLUTTER_WINDOW_