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

ash/shelf/shelf_window_watcher.h

Index: ash/shelf/shelf_window_watcher.h
diff --git a/ash/shelf/shelf_window_watcher.h b/ash/shelf/shelf_window_watcher.h
index 43ac4f0150ee7a328cd008108a13da08310883b8..0fb9d6975a10f17ad7ed2f8e220c69a4e785eb01 100644
--- a/ash/shelf/shelf_window_watcher.h
+++ b/ash/shelf/shelf_window_watcher.h
@@ -56,6 +56,26 @@ class ShelfWindowWatcher : public aura::client::ActivationChangeObserver,
     DISALLOW_COPY_AND_ASSIGN(RootWindowObserver);
   };
 
+  // Observer of removed Window that has an item.

[sky, 2014/01/08 15:01:49]

Change comments to:
Used to track windows that are removed. See description of ... for more details.

[simonhong, 2014/01/09 01:00:09]

Done.

+  // See the comments of ShelfWindowWatcher::StartObserveRemovedWindow() why
+  // removed window needs this observer.
+  class RemovedWindowObserver : public aura::WindowObserver {
+   public:
+    explicit RemovedWindowObserver(ShelfWindowWatcher* window_watcher);
+    virtual ~RemovedWindowObserver();
+
+   private:
+    // aura::WindowObserver overrides:
+    virtual void OnWindowParentChanged(aura::Window* window,
+                                       aura::Window* parent) OVERRIDE;
+    virtual void OnWindowDestroyed(aura::Window* window) OVERRIDE;
+
+    // Owned by Shell.
+    ShelfWindowWatcher* window_watcher_;
+
+    DISALLOW_COPY_AND_ASSIGN(RemovedWindowObserver);
+  };
+
   // Creates a LauncherItem for |window| that has LauncherItemDetails.
   void AddLauncherItem(aura::Window* window);
 
@@ -74,6 +94,17 @@ class ShelfWindowWatcher : public aura::client::ActivationChangeObserver,
   // Returns the index of LauncherItem associated with |window|.
   int GetLauncherItemIndexForWindow(aura::Window* window) const;
 
+  // Start observing removed |window| from ShelfWindowWatcher by
+  // RemovedWindowObserver. In some situations like dragging, it re-parents
+  // |window| to other container. But the item of |window| should not be
+  // removed immediately because |window| is not destroyed at that situation.
+  // We should observe to check whether |window| is destroyed or not.
+  void StartObserveRemovedWindow(aura::Window* window);

[sky, 2014/01/08 15:01:49]

StartObservingRemovedWindow

Used when a window is removed. During dragging a window may be removed and when
the drag completes added back. When this happens we don't want to remove the
launcher item. StartObservingRemovedWindow, if necessary, attaches and observer.
When done FinishObservingRemovedWindow() is invoked.

[simonhong, 2014/01/09 01:00:09]

Done.

+
+  // Stop observing |window| by RemovedWindowObserver and remove an item
+  // associated with |window|.
+  void FinishObserveRemovedWindow(aura::Window* window);

[simonhong, 2014/01/09 01:00:09]

Changed to FinishObservingRemovedWindow().

+
   // aura::client::ActivationChangeObserver overrides:
   virtual void OnWindowActivated(aura::Window* gained_active,
                                  aura::Window* lost_active) OVERRIDE;
@@ -97,12 +128,17 @@ class ShelfWindowWatcher : public aura::client::ActivationChangeObserver,
 
   RootWindowObserver root_window_observer_;
 
+  RemovedWindowObserver removed_window_observer_;
+
   // Holds all observed windows.
   ScopedObserver<aura::Window, aura::WindowObserver> observed_windows_;
 
   // Holds all observed root windows.
   ScopedObserver<aura::Window, aura::WindowObserver> observed_root_windows_;
 
+  // Holds removed windows that has an item from default container.
+  ScopedObserver<aura::Window, aura::WindowObserver> observed_removed_windows_;
+
   // Holds all observed activation clients.
   ScopedObserverWithDuplicatedSources<aura::client::ActivationClient,
       aura::client::ActivationChangeObserver> observed_activation_clients_;