Separate athena's startup process from AppShell's

athena/screen/public/screen_manager_delegate.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_SCREEN_PUBLIC_SCREEN_MANAGER_DELEGATE_H_
-#define ATHENA_SCREEN_PUBLIC_SCREEN_MANAGER_DELEGATE_H_
-
-#include "athena/athena_export.h"
-
-namespace gfx {
-class Insets;
-}
-
-namespace athena {
-
-// Delegate of the ScreenManager.
-class ATHENA_EXPORT ScreenManagerDelegate {
- public:
-  virtual ~ScreenManagerDelegate() {}
-
-  // Sets the screen's work area insets.
-  virtual void SetWorkAreaInsets(const gfx::Insets& insets) = 0;
-};
-
-}  // namespace athena
-
-#endif  // ATHENA_SCREEN_PUBLIC_SCREEN_MANAGER_DELEGATE_H_