Revert of athena: Add a minimized state for the home-card.

athena/wm/public/window_manager_observer.h

Index: athena/wm/public/window_manager_observer.h
diff --git a/athena/wm/public/window_manager_observer.h b/athena/wm/public/window_manager_observer.h
deleted file mode 100644
index e7f6bcfa610f862067b1be9b6d8727454089802f..0000000000000000000000000000000000000000
--- a/athena/wm/public/window_manager_observer.h
+++ /dev/null
@@ -1,25 +0,0 @@
-// 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_WINDOW_MANAGER_OBSERVER_H_
-#define ATHENA_SCREEN_PUBLIC_WINDOW_MANAGER_OBSERVER_H_
-
-#include "athena/athena_export.h"
-
-namespace athena {
-
-class ATHENA_EXPORT WindowManagerObserver {
- public:
-  virtual ~WindowManagerObserver() {}
-
-  // Called when the overview mode is displayed.
-  virtual void OnOverviewModeEnter() = 0;
-
-  // Called when going out of overview mode.
-  virtual void OnOverviewModeExit() = 0;
-};
-
-}  // namespace athena
-
-#endif  // ATHENA_SCREEN_PUBLIC_WINDOW_MANAGER_OBSERVER_H_