Introduce window container to be used by lock screen app windows

ash/wm/lock_layout_manager.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 ASH_WM_LOCK_LAYOUT_MANAGER_H_
 #define ASH_WM_LOCK_LAYOUT_MANAGER_H_
 
 #include "ash/ash_export.h"
 #include "ash/shell_observer.h"
 #include "ash/wm/wm_snap_to_pixel_layout_manager.h"
@@ skipping 48 matching lines @@
                              const gfx::Rect& new_bounds) override;
 
   // ShellObserver:
   void OnVirtualKeyboardStateChanged(bool activated,
                                      aura::Window* root_window) override;
 
   // keyboard::KeyboardControllerObserver overrides:
   void OnKeyboardBoundsChanging(const gfx::Rect& new_bounds) override;
   void OnKeyboardClosed() override;
 
- private:
+ protected:
   // Adjusts the bounds of all managed windows when the display area changes.
   // This happens when the display size, work area insets has changed.
   void AdjustWindowsForWorkAreaChange(const wm::WMEvent* event);
 
+  aura::Window* window() { return window_; }
+  aura::Window* root_window() { return root_window_; }
+
+ private:
   aura::Window* window_;
   aura::Window* root_window_;
 
   ScopedObserver<keyboard::KeyboardController,
                  keyboard::KeyboardControllerObserver>
       keyboard_observer_;
 
   // The bounds of the keyboard.
   gfx::Rect keyboard_bounds_;
 
   DISALLOW_COPY_AND_ASSIGN(LockLayoutManager);
 };
 
 }  // namespace ash
 
 #endif  // ASH_WM_LOCK_LAYOUT_MANAGER_H_