Sibling invalidation sets

Source/core/css/invalidation/InvalidationListData.cpp

 // Copyright 2015 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 "config.h"
-#include "modules/mediasession/MediaSession.h"
+#include "core/css/invalidation/InvalidationListData.h"
 
 namespace blink {
 
-MediaSession* MediaSession::create()
+DEFINE_TRACE(InvalidationListData)
 {
-    return new MediaSession;
-}
-
-void MediaSession::activate()
-{
-}
-
-void MediaSession::deactivate()
-{
+    visitor->trace(m_invalidationList[InvalidateDescendants]);
+    visitor->trace(m_invalidationList[InvalidateSiblings]);
 }
 
 } // namespace blink