Listen to Display reconfiguration and notify DisplayObservers on Mac.

ui/views/widget/desktop_aura/desktop_screen_x11.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 UI_VIEWS_WIDGET_DESKTOP_AURA_DESKTOP_SCREEN_X11_H_
 #define UI_VIEWS_WIDGET_DESKTOP_AURA_DESKTOP_SCREEN_X11_H_
 
-#include "base/observer_list.h"
 #include "base/timer/timer.h"
 #include "ui/events/platform/platform_event_dispatcher.h"
 #include "ui/gfx/screen.h"
+#include "ui/gfx/screen_display_observer_delegate.h"
 #include "ui/views/views_export.h"
 
 namespace gfx {
 class Display;
 }
 
 typedef unsigned long XID;
 typedef XID Window;
 typedef struct _XDisplay Display;
 
 namespace views {
 class DesktopScreenX11Test;
 
 // Our singleton screen implementation that talks to xrandr.
 class VIEWS_EXPORT DesktopScreenX11 : public gfx::Screen,
                                       public ui::PlatformEventDispatcher {
  public:
   DesktopScreenX11();
 
   virtual ~DesktopScreenX11();
 
-  // Takes a set of displays and dispatches the screen change events to
-  // listeners. Exposed for testing.
-  void ProcessDisplayChange(const std::vector<gfx::Display>& displays);
-
   // Overridden from gfx::Screen:
   virtual bool IsDIPEnabled() OVERRIDE;
   virtual gfx::Point GetCursorScreenPoint() OVERRIDE;
   virtual gfx::NativeWindow GetWindowUnderCursor() OVERRIDE;
   virtual gfx::NativeWindow GetWindowAtScreenPoint(const gfx::Point& point)
       OVERRIDE;
   virtual int GetNumDisplays() const OVERRIDE;
   virtual std::vector<gfx::Display> GetAllDisplays() const OVERRIDE;
   virtual gfx::Display GetDisplayNearestWindow(
       gfx::NativeView window) const OVERRIDE;
@@ skipping 32 matching lines @@
   // decoding events regarding output add/remove.
   int xrandr_event_base_;
 
   // The display objects we present to chrome.
   std::vector<gfx::Display> displays_;
 
   // The timer to delay configuring outputs. See also the comments in
   // Dispatch().
   scoped_ptr<base::OneShotTimer<DesktopScreenX11> > configure_timer_;
 
-  ObserverList<gfx::DisplayObserver> observer_list_;
+  ScreenDisplayObserverDelegate observer_delegate_;
 
   DISALLOW_COPY_AND_ASSIGN(DesktopScreenX11);
 };
 
 }  // namespace views
 
 #endif  // UI_VIEWS_WIDGET_DESKTOP_AURA_DESKTOP_SCREEN_X11_H_