Call UpdateControlButtonsVisibility() in OnMouseMoved().

ui/message_center/views/notification_view.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 "ui/message_center/views/notification_view.h"
 
 #include <stddef.h>
 
 #include "base/command_line.h"
 #include "base/macros.h"
@@ skipping 328 matching lines @@
   views::View::ScrollRectToVisible(GetLocalBounds());
 }
 
 gfx::NativeCursor NotificationView::GetCursor(const ui::MouseEvent& event) {
   if (!clickable_ || !controller()->HasClickedListener(notification_id()))
     return views::View::GetCursor(event);
 
   return views::GetNativeHandCursor();
 }
 
+void NotificationView::OnMouseMoved(const ui::MouseEvent& event) {
+  MessageView::OnMouseMoved(event);
+  UpdateControlButtonsVisibility();
+}
+
 void NotificationView::OnMouseEntered(const ui::MouseEvent& event) {
   MessageView::OnMouseEntered(event);
   UpdateControlButtonsVisibility();
 }
 
 void NotificationView::OnMouseExited(const ui::MouseEvent& event) {
   MessageView::OnMouseExited(event);
   UpdateControlButtonsVisibility();
 }
 
@@ skipping 396 matching lines @@
 
   return message_line_limit;
 }
 
 int NotificationView::GetMessageHeight(int width, int limit) const {
   return message_view_ ?
          message_view_->GetSizeForWidthAndLines(width, limit).height() : 0;
 }
 
 }  // namespace message_center