Provide default implementations for NotificationDelegate methods.

chrome/browser/sync/sync_error_notifier_ash.cc

Index: chrome/browser/sync/sync_error_notifier_ash.cc
diff --git a/chrome/browser/sync/sync_error_notifier_ash.cc b/chrome/browser/sync/sync_error_notifier_ash.cc
index 01e5dd2be101feb5113cc00ed24f423b01a4d6ec..4af01aa3204968925a3a38500002a735f5a733d4 100644
--- a/chrome/browser/sync/sync_error_notifier_ash.cc
+++ b/chrome/browser/sync/sync_error_notifier_ash.cc
@@ -45,10 +45,6 @@ class SyncNotificationDelegate : public NotificationDelegate {
                            Profile* profile);
 
   // NotificationDelegate:
-  void Display() override;
-  void Error() override;
-  void Close(bool by_user) override;
-  bool HasClickedListener() override;
   void Click() override;
   void ButtonClick(int button_index) override;
   std::string id() const override;
@@ -76,20 +72,6 @@ SyncNotificationDelegate::SyncNotificationDelegate(
 
 SyncNotificationDelegate::~SyncNotificationDelegate() {
 }
-
-void SyncNotificationDelegate::Display() {
-}
-
-void SyncNotificationDelegate::Error() {
-}
-
-void SyncNotificationDelegate::Close(bool by_user) {
-}
-
-bool SyncNotificationDelegate::HasClickedListener() {
-  return false;
-}
-
 void SyncNotificationDelegate::Click() {
   ShowSyncSetup();
 }