Replace base::CallbackList with base::ObserverList in CastConfigDelegate

chrome/browser/ui/ash/cast_config_delegate_media_router.h

 // Copyright 2015 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 CHROME_BROWSER_UI_ASH_CAST_CONFIG_DELEGATE_MEDIA_ROUTER_H_
 #define CHROME_BROWSER_UI_ASH_CAST_CONFIG_DELEGATE_MEDIA_ROUTER_H_
 
 #include "ash/cast_config_delegate.h"
 #include "base/macros.h"
+#include "base/observer_list.h"
 
 namespace media_router {
 class MediaRouter;
 }
 
 class CastDeviceCache;
 
 // A class which allows the ash tray to communicate with the media router.
 class CastConfigDelegateMediaRouter : public ash::CastConfigDelegate {
  public:
   CastConfigDelegateMediaRouter();
   ~CastConfigDelegateMediaRouter() override;
 
   // The MediaRouter is not always enabled. We only use this backend when it is
   // enabled.
   static bool IsEnabled();
   static void SetMediaRouterForTest(media_router::MediaRouter* media_router);
 
  private:
   // CastConfigDelegate:
   bool HasCastExtension() const override;
-  DeviceUpdateSubscription RegisterDeviceUpdateObserver(
-      const ReceiversAndActivitesCallback& callback) override;
+

[achuithb, 2016/01/13 09:21:25]

remove whitespace? Also I'd prefer Add/Remove Observer to be the last functions

[jdufault, 2016/01/13 19:43:26]

Done.

+  void AddObserver(ash::CastConfigDelegate::Observer* observer) override;
+  void RemoveObserver(ash::CastConfigDelegate::Observer* observer) override;
   void RequestDeviceRefresh() override;
   void CastToReceiver(const std::string& receiver_id) override;
   void StopCasting(const std::string& route_id) override;
   bool HasOptions() const override;
   void LaunchCastOptions() override;
 
   // |devices_| stores the current source/route status that we query from.
   // This will return null until the media router is initialized.
   CastDeviceCache* devices();
   scoped_ptr<CastDeviceCache> devices_;
 
-  base::CallbackList<void(const ReceiversAndActivities&)> callback_list_;
+  base::ObserverList<ash::CastConfigDelegate::Observer> observer_list_;
 
   DISALLOW_COPY_AND_ASSIGN(CastConfigDelegateMediaRouter);
 };
 
 #endif  // CHROME_BROWSER_UI_ASH_CAST_CONFIG_DELEGATE_MEDIA_ROUTER_H_