Revert of Oilpan: Move MediaStreamSource, MediaStreamComponent and MediaStreamDescriptor

Source/modules/mediastream/MediaStreamTrack.cpp

Index: Source/modules/mediastream/MediaStreamTrack.cpp
diff --git a/Source/modules/mediastream/MediaStreamTrack.cpp b/Source/modules/mediastream/MediaStreamTrack.cpp
index 38a01dcaf433b04a370f3fe01d3421d576c6c455..d12d45b5d23cdcfef64c59dae0c54415fb7de17c 100644
--- a/Source/modules/mediastream/MediaStreamTrack.cpp
+++ b/Source/modules/mediastream/MediaStreamTrack.cpp
@@ -59,6 +59,7 @@
 
 MediaStreamTrack::~MediaStreamTrack()
 {
+    m_component->source()->removeObserver(this);
 }
 
 String MediaStreamTrack::kind() const
@@ -146,9 +147,9 @@
 
 MediaStreamTrack* MediaStreamTrack::clone(ExecutionContext* context)
 {
-    MediaStreamComponent* clonedComponent = MediaStreamComponent::create(component()->source());
-    MediaStreamTrack* clonedTrack = MediaStreamTrack::create(context, clonedComponent);
-    MediaStreamCenter::instance().didCreateMediaStreamTrack(clonedComponent);
+    RefPtr<MediaStreamComponent> clonedComponent = MediaStreamComponent::create(component()->source());
+    MediaStreamTrack* clonedTrack = MediaStreamTrack::create(context, clonedComponent.get());
+    MediaStreamCenter::instance().didCreateMediaStreamTrack(clonedComponent.get());
     return clonedTrack;
 }
 
@@ -229,9 +230,7 @@
 void MediaStreamTrack::trace(Visitor* visitor)
 {
     visitor->trace(m_registeredMediaStreams);
-    visitor->trace(m_component);
     EventTargetWithInlineData::trace(visitor);
-    MediaStreamSource::Observer::trace(visitor);
 }
 
 } // namespace blink