Provide default implementations for NotificationDelegate methods.

chrome/browser/signin/signin_error_notifier_ash.cc

Index: chrome/browser/signin/signin_error_notifier_ash.cc
diff --git a/chrome/browser/signin/signin_error_notifier_ash.cc b/chrome/browser/signin/signin_error_notifier_ash.cc
index d1f9f5818f07271d8e43bbe27f49f13fc2482b69..a7d663ea074119c213982d7e80bc3ce173b5b636 100644
--- a/chrome/browser/signin/signin_error_notifier_ash.cc
+++ b/chrome/browser/signin/signin_error_notifier_ash.cc
@@ -50,10 +50,6 @@ class SigninNotificationDelegate : 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;
@@ -82,19 +78,6 @@ SigninNotificationDelegate::SigninNotificationDelegate(
 SigninNotificationDelegate::~SigninNotificationDelegate() {
 }
 
-void SigninNotificationDelegate::Display() {
-}
-
-void SigninNotificationDelegate::Error() {
-}
-
-void SigninNotificationDelegate::Close(bool by_user) {
-}
-
-bool SigninNotificationDelegate::HasClickedListener() {
-  return false;
-}
-
 void SigninNotificationDelegate::Click() {
   FixSignIn();
 }