Do not let go of MediaStreamTracks too early.

third_party/WebKit/Source/modules/mediastream/MediaStreamTrack.cpp

Index: third_party/WebKit/Source/modules/mediastream/MediaStreamTrack.cpp
diff --git a/third_party/WebKit/Source/modules/mediastream/MediaStreamTrack.cpp b/third_party/WebKit/Source/modules/mediastream/MediaStreamTrack.cpp
index 7130511d98579eaf69d0a8ad532b93abc20d54ab..2dbab3b640342811d0596e906da702aa77ea7db5 100644
--- a/third_party/WebKit/Source/modules/mediastream/MediaStreamTrack.cpp
+++ b/third_party/WebKit/Source/modules/mediastream/MediaStreamTrack.cpp
@@ -210,6 +210,11 @@ void MediaStreamTrack::stop()
     m_stopped = true;
 }
 
+bool MediaStreamTrack::hasPendingActivity() const
+{
+    return !m_stopped && hasEventListeners();

[sof, 2016/02/07 06:54:27]

I wonder if something effectively like this needs to be done for all
ActiveDOMObjects? It isn't done for several.

[sof, 2016/02/07 07:04:36]

I notice MajorGCWrapperVisitor has special handling for Nodes with event
listeners, but not ActiveDOMObjects.

[haraken, 2016/02/07 07:21:31]

Yeah, without having the check, we'll end up with keeping ActiveDOMObjects alive
longer than needed. So we should.

That said, we can't simply check hasEventListeners in V8GCController because
each ActiveDOMObject has its own semantics to keep the object alive. So I think
we need to manually add the hasEventListeners check to all
hasPendingActivity()'s that need the check.

+}
+
 PassOwnPtr<AudioSourceProvider> MediaStreamTrack::createWebAudioSource()
 {
     return MediaStreamCenter::instance().createWebAudioSourceFromMediaStreamTrack(component());