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;
 
   // 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 33 matching lines @@
   void UpdateStacking(aura::Window* active_window);
 
   // keyboard::KeyboardControllerObserver:
   virtual void OnKeyboardBoundsChanging(
       const gfx::Rect& keyboard_bounds) OVERRIDE;
 
   // Parent window associated with this layout manager.
   aura::Window* dock_container_;
   // Protect against recursive calls to Relayout().
   bool in_layout_;
+  // The former child being dragged.
+  aura::Window* dragged_former_child_;

[flackr, 2013/07/18 22:16:53]

Is there any reason not to use dragged_window_ for this? It seems like as long
as you allow dragged_window_ to not be a child of the dock container this should
work fine.

[varkha, 2013/07/18 22:58:14]

Not anymore - nice catch. Done.

   // The docked window being dragged.
   aura::Window* dragged_window_;
   // The launcher we are observing for launcher icon changes.
   Launcher* launcher_;
   // The shelf layout manager being observed for visibility changes.
   ShelfLayoutManager* shelf_layout_manager_;
   // Tracks the visibility of the shelf. Defaults to false when there is no
   // shelf.
   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 even if no windows are
+  // currently focused.
+  aura::Window* last_active_;
+
   // 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_