Reland of Use shared NotificationControlButtonsView for non-arc notification buttons

ui/message_center/views/notification_control_buttons_view.cc

 // Copyright 2017 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/notification_control_buttons_view.h"
 
 #include "ui/base/l10n/l10n_util.h"
 #include "ui/compositor/layer.h"
 #include "ui/events/event.h"
 #include "ui/gfx/animation/linear_animation.h"
@@ skipping 62 matching lines @@
     settings_button_->SetAccessibleName(l10n_util::GetStringUTF16(
         IDS_MESSAGE_NOTIFICATION_SETTINGS_BUTTON_ACCESSIBLE_NAME));
     settings_button_->SetTooltipText(l10n_util::GetStringUTF16(
         IDS_MESSAGE_NOTIFICATION_SETTINGS_BUTTON_ACCESSIBLE_NAME));
     settings_button_->SetBackground(
         views::CreateSolidBackground(SK_ColorTRANSPARENT));
 
     // Add the button at the first.
     DCHECK_LE(child_count(), 1);
     AddChildViewAt(settings_button_, 0);
-  } else if (!show && close_button_) {
+  } else if (!show && settings_button_) {
     RemoveChildView(settings_button_);
     settings_button_ = nullptr;
   }
 }
 
 void NotificationControlButtonsView::SetBackgroundColor(
     const SkColor& target_bgcolor) {
   if (background()->get_color() != target_bgcolor) {
     bgcolor_origin_ = background()->get_color();
     bgcolor_target_ = target_bgcolor;
@@ skipping 53 matching lines @@
     const gfx::Animation* animation) {
   // The animation is never cancelled explicitly.
   NOTREACHED();
 
   bgcolor_origin_ = bgcolor_target_;
   SetBackground(views::CreateSolidBackground(bgcolor_target_));
   SchedulePaint();
 }
 
 }  // namespace message_center