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

chrome/browser/ui/ash/cast_config_delegate_media_router.cc

Index: chrome/browser/ui/ash/cast_config_delegate_media_router.cc
diff --git a/chrome/browser/ui/ash/cast_config_delegate_media_router.cc b/chrome/browser/ui/ash/cast_config_delegate_media_router.cc
index 350505d0c6d290e144bc85adad90c5c6062c1e1a..fffd78c292bbecabeb8848407796972b69168afb 100644
--- a/chrome/browser/ui/ash/cast_config_delegate_media_router.cc
+++ b/chrome/browser/ui/ash/cast_config_delegate_media_router.cc
@@ -136,10 +136,14 @@ bool CastConfigDelegateMediaRouter::HasCastExtension() const {
   return true;
 }
 
-CastConfigDelegateMediaRouter::DeviceUpdateSubscription
-CastConfigDelegateMediaRouter::RegisterDeviceUpdateObserver(
-    const ReceiversAndActivitesCallback& callback) {
-  return callback_list_.Add(callback);
+void CastConfigDelegateMediaRouter::AddObserver(
+    ash::CastConfigDelegate::Observer* observer) {
+  observer_list_.AddObserver(observer);
+}
+
+void CastConfigDelegateMediaRouter::RemoveObserver(
+    ash::CastConfigDelegate::Observer* observer) {
+  observer_list_.RemoveObserver(observer);
 }
 
 void CastConfigDelegateMediaRouter::RequestDeviceRefresh() {
@@ -192,7 +196,8 @@ void CastConfigDelegateMediaRouter::RequestDeviceRefresh() {
     }
   }
 
-  callback_list_.Notify(items);
+  FOR_EACH_OBSERVER(ash::CastConfigDelegate::Observer, observer_list_,
+                    OnDevicesUpdated(items));
 }
 
 void CastConfigDelegateMediaRouter::CastToReceiver(