Oilpan: fix build after r201727.

TBR=oilpan-reviews
BUG=262211
NOTRY=true

Review URL: https://codereview.chromium.org/1329753003

git-svn-id: svn://svn.chromium.org/blink/trunk@201733 bbb929c8-8fbe-4397-9dbb-9b2b20218538

third_party/WebKit/Source/modules/mediarecorder/MediaRecorder.cpp

@@ -284,6 +284,7 @@ void MediaRecorder::dispatchScheduledEvent()
 DEFINE_TRACE(MediaRecorder)
 {
     visitor->trace(m_stream);
+    visitor->trace(m_scheduledEvents);
     RefCountedGarbageCollectedEventTargetWithInlineData<MediaRecorder>::trace(visitor);
     ActiveDOMObject::trace(visitor);
 }