[ash] Don't remove an item when associated window is dragged

ash/shelf/shelf_window_watcher.h

 // Copyright 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_SHELF_SHELF_WINDOW_WATCHER_H_
 #define ASH_SHELF_SHELF_WINDOW_WATCHER_H_
 
 #include "ash/shelf/scoped_observer_with_duplicated_sources.h"
 #include "base/basictypes.h"
 #include "base/compiler_specific.h"
@@ skipping 63 matching lines @@
   // Returns the index of LauncherItem associated with |window|.
   int GetLauncherItemIndexForWindow(aura::Window* window) const;
 
   // aura::client::ActivationChangeObserver overrides:
   virtual void OnWindowActivated(aura::Window* gained_active,
                                  aura::Window* lost_active) OVERRIDE;
 
   // aura::WindowObserver overrides:
   virtual void OnWindowAdded(aura::Window* window) OVERRIDE;
   virtual void OnWillRemoveWindow(aura::Window* window) OVERRIDE;
+  virtual void OnWindowParentChanged(aura::Window* window,
+                                     aura::Window* parent) OVERRIDE;
   virtual void OnWindowDestroying(aura::Window* window) OVERRIDE;
   virtual void OnWindowPropertyChanged(aura::Window* window,
                                        const void* key,
                                        intptr_t old) OVERRIDE;
 
   // gfx::DisplayObserver overrides:
   virtual void OnDisplayBoundsChanged(const gfx::Display& display) OVERRIDE;
   virtual void OnDisplayAdded(const gfx::Display& display) OVERRIDE;
   virtual void OnDisplayRemoved(const gfx::Display& old_display) OVERRIDE;
 
@@ skipping 13 matching lines @@
   ScopedObserverWithDuplicatedSources<aura::client::ActivationClient,
       aura::client::ActivationChangeObserver> observed_activation_clients_;
 
   DISALLOW_COPY_AND_ASSIGN(ShelfWindowWatcher);
 };
 
 }  // namespace internal
 }  // namespace ash
 
 #endif  // ASH_SHELF_SHELF_WINDOW_WATCHER_H_