Introduces AppActivity and handler of chrome.shell API.

athena/main/athena_app_window_controller.h

+// Copyright 2014 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef ATHENA_MAIN_ATHENA_APP_WINDOW_CONTROLLER_H_
+#define ATHENA_MAIN_ATHENA_APP_WINDOW_CONTROLLER_H_
+
+#include "apps/shell/browser/shell_app_window_controller.h"
+#include "base/macros.h"
+
+namespace athena {
+
+// The shell app window controller for athena.

[James Cook, 2014/06/16 16:12:31]

nit: Could you describe briefly what this class is expected to do?  Open apps in
fullscreen?  Just associate app windows with the window manager?

[Jun Mukai, 2014/06/16 17:46:52]

The web contents are embedded into an athena's activity; added comments.

+class AthenaAppWindowController : public apps::ShellAppWindowController {
+ public:
+  AthenaAppWindowController();
+  virtual ~AthenaAppWindowController();
+
+  // Overridden from apps::ShellAppWindowController:
+  virtual apps::ShellAppWindow* CreateAppWindow(
+      content::BrowserContext* context) OVERRIDE;
+  virtual void CloseAppWindows() OVERRIDE;
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(AthenaAppWindowController);
+};
+
+}  // namespace athena
+
+#endif  // ATHENA_MAIN_ATHENA_APP_WINDOW_CONTROLLER_H_