Aura: Add non-browser windows into the list of "Alt + Tab" cycle list.

ui/aura/client/activation_client.h

 // Copyright (c) 2012 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"
 #include "ui/aura/window.h"
@@ skipping 15 matching lines @@
   // 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;
 
   // Invoked prior to |window| getting focus as a result of the |event|. |event|
   // may be NULL. Returning false blocks |window| from getting focus.
   virtual bool OnWillFocusWindow(Window* window, const Event* event) = 0;
 
+  // Returns true if |window| can be activated, false otherwise. If |window| has
+  // a modal child it can not be activated.
+  virtual bool CanActivateWindow(Window* window) const = 0;
+
  protected:
   virtual ~ActivationClient() {}
 };
 
 // Sets/Gets the activation client on the RootWindow.
 AURA_EXPORT void SetActivationClient(RootWindow* root_window,
                                      ActivationClient* client);
 AURA_EXPORT ActivationClient* GetActivationClient(RootWindow* root_window);
 
 // A property key to store what the client defines as the active window on the
 // RootWindow.
 AURA_EXPORT extern const WindowProperty<Window*>* const
     kRootWindowActiveWindowKey;
 
 // Some types of transient window are only visible when active.
 // The transient parents of these windows may have visual appearance properties
 // that differ from transient parents that can be deactivated.
 // The presence of this property implies these traits.
 // TODO(beng): currently the UI framework (views) implements the actual
 //             close-on-deactivate component of this feature but it should be
 //             possible to implement in the aura client.
 AURA_EXPORT void SetHideOnDeactivate(Window* window, bool hide_on_deactivate);
 AURA_EXPORT bool GetHideOnDeactivate(Window* window);
 
 }  // namespace clients
 }  // namespace aura
 
 #endif  // UI_AURA_CLIENT_ACTIVATION_CLIENT_H_