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

chrome/browser/extensions/api/cast_devices_private/cast_devices_private_api.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_EXTENSIONS_API_CAST_DEVICES_PRIVATE_CAST_DEVICES_PRIVATE_API_H_
 #define CHROME_BROWSER_EXTENSIONS_API_CAST_DEVICES_PRIVATE_CAST_DEVICES_PRIVATE_API_H_
 
 #include <vector>
 
 #include "ash/cast_config_delegate.h"
 #include "base/callback_list.h"
 #include "base/macros.h"
+#include "base/observer_list.h"
 #include "extensions/browser/browser_context_keyed_api_factory.h"
 #include "extensions/browser/extension_function.h"
 
 namespace extensions {
 
 class CastDeviceUpdateListeners : public BrowserContextKeyedAPI {
  public:
   explicit CastDeviceUpdateListeners(content::BrowserContext* context);
   ~CastDeviceUpdateListeners() override;
 
-  // Fetch an instance for the given context.
+  // Fetches an instance for the given context.
   static CastDeviceUpdateListeners* Get(content::BrowserContext* context);
 
-  // Register a function that will be invoked only when a new device update is
-  // available.
-  ash::CastConfigDelegate::DeviceUpdateSubscription RegisterCallback(
-      const ash::CastConfigDelegate::ReceiversAndActivitesCallback& callback);
+  // Adds an observer that will be invoked when new device data is available.
+  void AddObserver(ash::CastConfigDelegate::Observer* observer);
+  void RemoveObserver(ash::CastConfigDelegate::Observer* observer);
 
   // BrowserContextKeyedAPI implementation:
   static BrowserContextKeyedAPIFactory<CastDeviceUpdateListeners>*
   GetFactoryInstance();
   static const bool kServiceIsCreatedWithBrowserContext = false;
 
  private:
   using ReceiverAndActivityList =
     std::vector<ash::CastConfigDelegate::ReceiverAndActivity>;
 
   friend class CastDevicesPrivateUpdateDevicesFunction;  // For NotifyCallbacks.
   void NotifyCallbacks(const ReceiverAndActivityList& devices);
 
-  base::CallbackList<void(const ReceiverAndActivityList&)> callback_list_;
+  base::ObserverList<ash::CastConfigDelegate::Observer> observer_list_;
 
   friend class BrowserContextKeyedAPIFactory<CastDeviceUpdateListeners>;
 
   // BrowserContextKeyedAPI implementation:
   static const char* service_name() { return "CastDeviceUpdateListeners"; }
 
   DISALLOW_COPY_AND_ASSIGN(CastDeviceUpdateListeners);
 };
 
 // static void updateDeviceState(ReceiverActivity[] devices);
 class CastDevicesPrivateUpdateDevicesFunction :
     public UIThreadExtensionFunction {
  public:
   CastDevicesPrivateUpdateDevicesFunction();
 
  private:
   ~CastDevicesPrivateUpdateDevicesFunction() override;
 
   // ExtensionFunction:
   ResponseAction Run() override;
 
   DECLARE_EXTENSION_FUNCTION("cast.devicesPrivate.updateDevices",
                              CASTDEVICESPRIVATE_UPDATEDEVICES);
   DISALLOW_COPY_AND_ASSIGN(CastDevicesPrivateUpdateDevicesFunction);
 };
 
 }  // namespace extensions
 
 #endif  // CHROME_BROWSER_EXTENSIONS_API_CAST_DEVICES_PRIVATE_CAST_DEVICES_PRIVATE_API_H_