Provide default implementations for NotificationDelegate methods.

ash/system/chromeos/screen_security/screen_tray_item.cc

 // Copyright 2013 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 "ash/system/chromeos/screen_security/screen_tray_item.h"
 
 #include "ash/system/tray/fixed_sized_image_view.h"
 #include "ash/system/tray/tray_constants.h"
 #include "ui/base/resource/resource_bundle.h"
 #include "ui/message_center/message_center.h"
@@ skipping 98 matching lines @@
 }
 
 ScreenNotificationDelegate::ScreenNotificationDelegate(
     ScreenTrayItem* screen_tray)
   : screen_tray_(screen_tray) {
 }
 
 ScreenNotificationDelegate::~ScreenNotificationDelegate() {
 }
 
-void ScreenNotificationDelegate::Display() {
-}
-
-void ScreenNotificationDelegate::Error() {
-}
-
-void ScreenNotificationDelegate::Close(bool by_user) {
-}
-
-void ScreenNotificationDelegate::Click() {
-}
-
 void ScreenNotificationDelegate::ButtonClick(int button_index) {
   DCHECK_EQ(0, button_index);
   screen_tray_->Stop();
 }
 
 }  // namespace tray
 
 ScreenTrayItem::ScreenTrayItem(SystemTray* system_tray)
     : SystemTrayItem(system_tray),
       tray_view_(NULL),
@@ skipping 61 matching lines @@
   views::BoxLayout::Orientation layout =
       (alignment == ash::SHELF_ALIGNMENT_BOTTOM ||
        alignment == ash::SHELF_ALIGNMENT_TOP)
           ? views::BoxLayout::kHorizontal
           : views::BoxLayout::kVertical;
   tray_view_->SetLayoutManager(new views::BoxLayout(layout, 0, 0, 0));
   tray_view_->Layout();
 }
 
 }  // namespace ash