[Ozone-DRI] Add display observer

ui/ozone/platform/dri/screen_manager.h

 // Copyright 2014 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_OZONE_PLATFORM_DRI_SCREEN_MANAGER_H_
 #define UI_OZONE_PLATFORM_DRI_SCREEN_MANAGER_H_
 
 #include "base/macros.h"
 #include "base/memory/scoped_vector.h"
-#include "base/memory/weak_ptr.h"
+#include "base/observer_list.h"
+#include "ui/ozone/platform/dri/display_change_observer.h"
 #include "ui/ozone/platform/dri/hardware_display_controller.h"
 
 typedef struct _drmModeModeInfo drmModeModeInfo;
 
 namespace gfx {
 class Point;
 class Rect;
 class Size;
 }  // namespace gfx
 
@@ skipping 21 matching lines @@
   bool ConfigureDisplayController(uint32_t crtc,
                                   uint32_t connector,
                                   const gfx::Point& origin,
                                   const drmModeModeInfo& mode);
 
   // Disable the display controller identified by |crtc|. Note, the controller
   // may still be connected, so this does not remove the controller.
   bool DisableDisplayController(uint32_t crtc);
 
   // Returns a reference to the display controller configured to display within
-  // |bounds|.
-  // This returns a weak reference since the display controller may be destroyed
-  // at any point in time, but the changes are propagated to the compositor much
-  // later (Compositor owns SurfaceOzone*, which is responsible for updating the
-  // display surface).
-  base::WeakPtr<HardwareDisplayController> GetDisplayController(
-      const gfx::Rect& bounds);
+  // |bounds|. If the caller caches the controller it must also register as an
+  // observer to be notified when the controller goes out of scope.
+  HardwareDisplayController* GetDisplayController(const gfx::Rect& bounds);
+
+  void AddObserver(DisplayChangeObserver* observer);
+  void RemoveObserver(DisplayChangeObserver* observer);
 
   // On non CrOS builds there is no display configurator to look-up available
   // displays and initialize the HDCs. In such cases this is called internally
   // to initialize a display.
   virtual void ForceInitializationOfPrimaryDisplay();
 
  private:
   typedef ScopedVector<HardwareDisplayController> HardwareDisplayControllers;
 
   // Returns an iterator into |controllers_| for the controller identified by
@@ skipping 16 matching lines @@
   bool HandleMirrorMode(HardwareDisplayControllers::iterator original,
                         HardwareDisplayControllers::iterator mirror,
                         uint32_t crtc,
                         uint32_t connector);
 
   DriWrapper* dri_;  // Not owned.
   ScanoutBufferGenerator* buffer_generator_;  // Not owned.
   // List of display controllers (active and disabled).
   HardwareDisplayControllers controllers_;
 
+  ObserverList<DisplayChangeObserver> observers_;
+
   DISALLOW_COPY_AND_ASSIGN(ScreenManager);
 };
 
 }  // namespace ui
 
 #endif  // UI_OZONE_PLATFORM_DRI_SCREEN_MANAGER_H_