Revert "Remove aura and make a pure mojo::View version of the aura::Window FocusController."

mojo/services/window_manager/focus_controller_observer.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 MOJO_SERVICES_WINDOW_MANAGER_FOCUS_CONTROLLER_OBSERVER_H_
-#define MOJO_SERVICES_WINDOW_MANAGER_FOCUS_CONTROLLER_OBSERVER_H_
-
-namespace mojo {
-
-class View;
-
-class FocusControllerObserver {
- public:
-  // Called when |active| gains focus, or there is no active view
-  // (|active| is null in this case.) |old_active| refers to the
-  // previous active view or null if there was no previously active
-  // view.
-  virtual void OnViewActivated(View* gained_active,
-                               View* lost_active) = 0;
-
-  // Called when focus moves from |lost_focus| to |gained_focus|.
-  virtual void OnViewFocused(View* gained_focus, View* lost_focus) = 0;
-
-  // Called when during view activation the currently active view is
-  // selected for activation. This can happen when a view requested for
-  // activation cannot be activated because a system modal view is active.
-  virtual void OnAttemptToReactivateView(View* request_active,
-                                         View* actual_active) {}
-
- protected:
-  virtual ~FocusControllerObserver() {}
-};
-
-}  // namespace mojo
-
-#endif  // MOJO_SERVICES_WINDOW_MANAGER_FOCUS_CONTROLLER_OBSERVER_H_