Provide default implementations for NotificationDelegate methods.

chrome/browser/background/background_contents_service.cc

 // Copyright (c) 2012 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.
 
 #include "chrome/browser/background/background_contents_service.h"
 
 #include "apps/app_load_service.h"
 #include "base/basictypes.h"
 #include "base/bind.h"
 #include "base/command_line.h"
@@ skipping 86 matching lines @@
 class CrashNotificationDelegate : public NotificationDelegate {
  public:
   CrashNotificationDelegate(Profile* profile,
                             const Extension* extension)
       : profile_(profile),
         is_hosted_app_(extension->is_hosted_app()),
         is_platform_app_(extension->is_platform_app()),
         extension_id_(extension->id()) {
   }
 
-  void Display() override {}
-
-  void Error() override {}
-
-  void Close(bool by_user) override {}
-
   void Click() override {
     // http://crbug.com/247790 involves a crash notification balloon being
     // clicked while the extension isn't in the TERMINATED state. In that case,
     // any of the "reload" methods called below can unload the extension, which
     // indirectly destroys *this, invalidating all the member variables, so we
     // copy the extension ID before using it.
     std::string copied_extension_id = extension_id_;
     if (is_hosted_app_) {
       // There can be a race here: user clicks the balloon, and simultaneously
       // reloads the sad tab for the app. So we check here to be safe before
@@ skipping 653 matching lines @@
     bool user_gesture,
     bool* was_blocked) {
   Browser* browser = chrome::FindLastActiveWithProfile(
       Profile::FromBrowserContext(new_contents->GetBrowserContext()),
       chrome::GetActiveDesktop());
   if (browser) {
     chrome::AddWebContents(browser, NULL, new_contents, disposition,
                            initial_pos, user_gesture, was_blocked);
   }
 }