Revert 114095 - Move the concept of Activation to the Shell.

ui/aura/client/activation_client.h

-// Copyright (c) 2011 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 UI_AURA_CLIENT_ACTIVATION_CLIENT_H_
-#define UI_AURA_CLIENT_ACTIVATION_CLIENT_H_
-#pragma once
-
-#include "ui/aura/aura_export.h"
-
-namespace aura {
-
-class Window;
-
-// An interface implemented by an object that manages window activation.
-class AURA_EXPORT ActivationClient {
- public:
-  // Sets/Gets the activation client on the RootWindow.
-  static void SetActivationClient(ActivationClient* client);
-  static ActivationClient* GetActivationClient();
-
-  // Activates |window|. If |window| is NULL, nothing happens.
-  virtual void ActivateWindow(Window* window) = 0;
-
-  // Deactivates |window|. What (if anything) is activated next is up to the
-  // client. If |window| is NULL, nothing happens.
-  virtual void DeactivateWindow(Window* window) = 0;
-
-  // Retrieves the active window, or NULL if there is none.
-  virtual aura::Window* GetActiveWindow() = 0;
-
-  // Returns true if |window| can be focused. To be focusable, |window| must
-  // exist inside an activatable window.
-  virtual bool CanFocusWindow(Window* window) const = 0;
-
- protected:
-  virtual ~ActivationClient() {}
-};
-
-}  // namespace aura
-
-#endif  // UI_AURA_CLIENT_ACTIVATION_CLIENT_H_