Implement automatic layout and stacking for docked windows

ash/wm/dock/docked_window_layout_manager.h

 // Copyright (c) 2013 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_DOCK_DOCKED_WINDOW_LAYOUT_MANAGER_H_
 #define ASH_WM_DOCK_DOCKED_WINDOW_LAYOUT_MANAGER_H_
 
 #include "ash/ash_export.h"
 #include "ash/shelf/shelf_layout_manager_observer.h"
 #include "ash/shell_observer.h"
@@ skipping 85 matching lines @@
   virtual void SetChildBounds(aura::Window* child,
                               const gfx::Rect& requested_bounds) OVERRIDE;
 
   // ash::ShellObserver:
   virtual void OnShelfAlignmentChanged(aura::RootWindow* root_window) OVERRIDE;
 
   // aura::WindowObserver:
   virtual void OnWindowPropertyChanged(aura::Window* window,
                                        const void* key,
                                        intptr_t old) OVERRIDE;
+  virtual void OnWindowBoundsChanged(aura::Window* window,
+                                     const gfx::Rect& old_bounds,
+                                     const gfx::Rect& new_bounds) OVERRIDE;
+  virtual void OnWindowDestroying(aura::Window* window) OVERRIDE;
 
   // aura::client::ActivationChangeObserver:
   virtual void OnWindowActivated(aura::Window* gained_active,
                                  aura::Window* lost_active) OVERRIDE;
 
   // ShelfLayoutManagerObserver:
   virtual void WillChangeVisibilityState(
       ShelfVisibilityState new_state) OVERRIDE;
 
  private:
@@ skipping 51 matching lines @@
   bool shelf_hidden_;
   // Current width of the dock.
   int docked_width_;
 
   // Last bounds that were sent to observers.
   gfx::Rect docked_bounds_;
 
   // Side of the screen that the dock is positioned at.
   DockedAlignment alignment_;
 
+  // The last active window. Used to maintain stacking order even if no windows
+  // are currently focused.
+  aura::Window* last_active_window_;
+
   // Observers of dock bounds changes.
   ObserverList<DockedWindowLayoutManagerObserver> observer_list_;
 
   DISALLOW_COPY_AND_ASSIGN(DockedWindowLayoutManager);
 };
 
 }  // namespace internal
 }  // namespace ash
 
 #endif  // ASH_WM_DOCK_DOCKED_WINDOW_LAYOUT_MANAGER_H_