Reduce ActiveDOMObjects from core/

third_party/WebKit/Source/core/streams/UnderlyingSourceBase.cpp

Index: third_party/WebKit/Source/core/streams/UnderlyingSourceBase.cpp
diff --git a/third_party/WebKit/Source/core/streams/UnderlyingSourceBase.cpp b/third_party/WebKit/Source/core/streams/UnderlyingSourceBase.cpp
index 150d8ab4a574996d80e4d97d000c266d932b93c9..9af2adda50e56e36436df7e3e68f0fe96e7fc50a 100644
--- a/third_party/WebKit/Source/core/streams/UnderlyingSourceBase.cpp
+++ b/third_party/WebKit/Source/core/streams/UnderlyingSourceBase.cpp
@@ -55,7 +55,7 @@ bool UnderlyingSourceBase::hasPendingActivity() const
     return m_controller && m_controller->isActive();
 }
 
-void UnderlyingSourceBase::stop()
+void UnderlyingSourceBase::contextDestroyed()
 {
     m_controller->noteHasBeenCanceled();
     m_controller.clear();
@@ -63,8 +63,8 @@ void UnderlyingSourceBase::stop()
 
 DEFINE_TRACE(UnderlyingSourceBase)
 {
-    ActiveDOMObject::trace(visitor);
     visitor->trace(m_controller);
+    ContextLifecycleObserver::trace(visitor);
 }
 
 } // namespace blink