aura: Some changes in Window and Desktop.

ui/aura/desktop.h

 // Copyright (c) 2011 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 UI_AURA_DESKTOP_H_
 #define UI_AURA_DESKTOP_H_
 #pragma once
 
 #include "base/basictypes.h"
 #include "base/memory/ref_counted.h"
@@ skipping 13 matching lines @@
 
 namespace aura {
 
 class DesktopDelegate;
 class DesktopHost;
 class MouseEvent;
 
 // Desktop is responsible for hosting a set of windows.
 class AURA_EXPORT Desktop : public ui::CompositorDelegate {
  public:
+  // Observers can listen to various events on the Desktop.
+  class Observer {
+   public:
+    virtual void OnDesktopResized(const gfx::Size& new_size) {}

[sky, 2011/10/12 21:11:27]

I think we should make these pure virtual. Also, add a protected virtual
destructor and move this into its own header.

[sadrul, 2011/10/12 21:33:23]

Done. I kept the empty implementation for WindowObserver: an observer may only
be interested in one particular event, so it shouldn't be forced to provide
implementations for all the possible events.

+  };
+
   Desktop();
   virtual ~Desktop();
 
   DesktopDelegate* delegate() { return delegate_.get(); }
   void SetDelegate(DesktopDelegate* delegate);
 
   // Initializes the desktop.
   void Init();
 
   // Shows the desktop host.
@@ skipping 49 matching lines @@
 
   // Invoked from RootWindow when |window| is being destroyed.
   void WindowDestroying(Window* window);
 
   // Returns the desktop's dispatcher. The result should only be passed to
   // MessageLoopForUI::Run() or MessageLoopForUI::RunAllPendingWithDispatcher(),
   // or used to dispatch an event by |Dispatch(const NativeEvent&)| on it.
   // It must never be stored.
   MessageLoop::Dispatcher* GetDispatcher();
 
+  // Add/remove observer.
+  void AddObserver(Observer* observer);
+  void RemoveObserver(Observer* observer);
+  bool HasObserver(Observer* observer);

[sky, 2011/10/12 21:11:27]

Unless we need HasObserver, don't add it.

[sadrul, 2011/10/12 21:33:23]

It's not needed right now. Removed.

+
   static Desktop* GetInstance();
 
  private:
   // Overridden from ui::CompositorDelegate
   virtual void ScheduleDraw();
 
   scoped_ptr<DesktopDelegate> delegate_;
 
   scoped_refptr<ui::Compositor> compositor_;
 
   scoped_ptr<internal::RootWindow> window_;
 
   scoped_ptr<DesktopHost> host_;
 
   static Desktop* instance_;
 
   // Used to schedule painting.
   base::WeakPtrFactory<Desktop> schedule_paint_factory_;
 
   // Factory used to create Compositors. Settable by tests.
   static ui::Compositor*(*compositor_factory_)();
 
   Window* active_window_;
 
   // Are we in the process of being destroyed? Used to avoid processing during
   // destruction.
   bool in_destructor_;
 
+  ObserverList<Observer> observers_;
+
   DISALLOW_COPY_AND_ASSIGN(Desktop);
 };
 
 }  // namespace aura
 
 #endif  // UI_AURA_DESKTOP_H_