Prepare SystemTray to support notifications

ash/system/tray_update.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 "ash/system/tray_update.h"
 
 #include "ash/shell.h"
 #include "ash/system/tray/system_tray_delegate.h"
 #include "ash/system/tray/tray_constants.h"
 #include "ash/system/tray/tray_views.h"
@@ skipping 39 matching lines @@
 
   DISALLOW_COPY_AND_ASSIGN(UpdateView);
 };
 
 }
 
 namespace ash {
 namespace internal {
 
 TrayUpdate::TrayUpdate()
-    : TrayImageItem(IDR_AURA_UBER_TRAY_UPDATE) {
+    : TrayImageItem(IDR_AURA_UBER_TRAY_UPDATE),
+      default_(NULL) {
 }
 
 TrayUpdate::~TrayUpdate() {}
 
 bool TrayUpdate::GetInitialVisibility() {
   return Shell::GetInstance()->tray_delegate()->SystemShouldUpgrade();
 }
 
 views::View* TrayUpdate::CreateDefaultView(user::LoginStatus status) {
   if (!Shell::GetInstance()->tray_delegate()->SystemShouldUpgrade())
     return NULL;
-  default_.reset(new UpdateView);
-  return default_.get();
+  DCHECK(default_ == NULL);
+  default_ = new UpdateView;
+  return default_;
 }
 
 void TrayUpdate::DestroyDefaultView() {
-  default_.reset();
+  default_ = NULL;
 }
 
 void TrayUpdate::OnUpdateRecommended() {
   tray_view()->SetVisible(true);
 }
 
 }  // namespace internal
 }  // namespace ash