Fix use-after-free in MessageListView.

ui/message_center/views/message_center_view.cc

 // Copyright (c) 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 "ui/message_center/views/message_center_view.h"
 
 #include <list>
 #include <map>
 
 #include "base/macros.h"
@@ skipping 159 matching lines @@
 
 void MessageCenterView::SetSettingsVisible(bool visible) {
   settings_visible_ = visible;
   Update(true /* animate */);
 }
 
 void MessageCenterView::ClearAllClosableNotifications() {
   if (is_closing_)
     return;
 
-  is_clearing_ = true;
+  is_clearing_all_notifications_ = true;
   UpdateButtonBarStatus();
   SetViewHierarchyEnabled(scroller_, false);
   message_list_view_->ClearAllClosableNotifications(
       scroller_->GetVisibleRect());
 }
 
 void MessageCenterView::OnAllNotificationsCleared() {
-  is_clearing_ = false;
+  is_clearing_all_notifications_ = false;
   SetViewHierarchyEnabled(scroller_, true);
   button_bar_->SetCloseAllButtonEnabled(false);
 
   // The status of buttons will be updated after removing all notifications.
 
   // Action by user.
   message_center_->RemoveAllNotifications(
       true /* by_user */,
       message_center::MessageCenter::RemoveType::NON_PINNED);
 }
@@ skipping 419 matching lines @@
   }
   settings_transition_animation_.reset(new gfx::MultiAnimation(
       parts, base::TimeDelta::FromMicroseconds(1000000 / kDefaultFrameRateHz)));
   settings_transition_animation_->set_delegate(this);
   settings_transition_animation_->set_continuous(false);
   settings_transition_animation_->Start();
 }
 
 void MessageCenterView::UpdateButtonBarStatus() {
   // Disables all buttons during animation of cleaning of all notifications.
-  if (is_clearing_) {
+  if (is_clearing_all_notifications_) {
     button_bar_->SetSettingsAndQuietModeButtonsEnabled(false);
     button_bar_->SetCloseAllButtonEnabled(false);
     return;
   }
 
   button_bar_->SetBackArrowVisible(mode_ == Mode::SETTINGS);
   button_bar_->SetButtonsVisible(!is_locked_);
   button_bar_->SetTitle(GetButtonBarTitle());
 
   if (!is_locked_)
@@ skipping 48 matching lines @@
       }
       break;
     }
   }
 
   // Notify accessibility that the contents have changed.
   view->NotifyAccessibilityEvent(ui::AX_EVENT_CHILDREN_CHANGED, false);
 }
 
 }  // namespace message_center