Sibling invalidation sets

Source/core/css/invalidation/InvalidationListData.cpp

Index: Source/core/css/invalidation/InvalidationListData.cpp
diff --git a/Source/modules/mediasession/MediaSession.cpp b/Source/core/css/invalidation/InvalidationListData.cpp
similarity index 52%
copy from Source/modules/mediasession/MediaSession.cpp
copy to Source/core/css/invalidation/InvalidationListData.cpp
index 937bf7f19d23f26aadf5c3f1ae0393ae0050d093..c47a769f6aed296e1b86d4ea5fa39dcea4c87ce5 100644
--- a/Source/modules/mediasession/MediaSession.cpp
+++ b/Source/core/css/invalidation/InvalidationListData.cpp
@@ -3,21 +3,14 @@
 // found in the LICENSE file.
 
 #include "config.h"
-#include "modules/mediasession/MediaSession.h"
+#include "core/css/invalidation/InvalidationListData.h"
 
 namespace blink {
 
-MediaSession* MediaSession::create()
-{
-    return new MediaSession;
-}
-
-void MediaSession::activate()
-{
-}
-
-void MediaSession::deactivate()
+DEFINE_TRACE(InvalidationListData)
 {
+    visitor->trace(m_invalidationList[InvalidateDescendants]);
+    visitor->trace(m_invalidationList[InvalidateSiblings]);
 }
 
 } // namespace blink