[Athena: Cleanup] consolidate ChromeAppActivity and ShellAppActivity

athena/content/shell/shell_app_activity.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_CONTENT_SHELL_SHELL_APP_ACTIVITY_H_
-#define ATHENA_CONTENT_SHELL_SHELL_APP_ACTIVITY_H_
-
-#include "athena/content/app_activity.h"
-
-#include "base/memory/scoped_ptr.h"
-
-namespace extensions {
-class AppWindow;
-}
-
-namespace athena {
-
-class ShellAppActivity : public AppActivity {
- public:
-  explicit ShellAppActivity(extensions::AppWindow* app_window);
-  virtual ~ShellAppActivity();
-
- private:
-  // ActivityViewModel:
-  virtual views::Widget* CreateWidget() OVERRIDE;
-
-  // AppActivity:
-  virtual views::WebView* GetWebView() OVERRIDE;
-
-  extensions::AppWindow* app_window_;
-
-  DISALLOW_COPY_AND_ASSIGN(ShellAppActivity);
-};
-
-}  // namespace athena
-
-#endif  // ATHENA_CONTENT_SHELL_SHELL_APP_ACTIVITY_H_