Revert of Reduce ActiveDOMObjects from core/

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

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "core/streams/UnderlyingSourceBase.h"
 
 #include "bindings/core/v8/ScriptPromise.h"
 #include "bindings/core/v8/ScriptState.h"
 #include "bindings/core/v8/ScriptValue.h"
 #include "core/streams/ReadableStreamController.h"
@@ skipping 37 matching lines @@
 
 bool UnderlyingSourceBase::hasPendingActivity() const
 {
     // This will return false within a finite time period _assuming_ that
     // consumers use the controller to close or error the stream.
     // Browser-created readable streams should always close or error within a
     // finite time period, due to timeouts etc.
     return m_controller && m_controller->isActive();
 }
 
-void UnderlyingSourceBase::contextDestroyed()
+void UnderlyingSourceBase::stop()
 {
     m_controller->noteHasBeenCanceled();
     m_controller.clear();
 }
 
 DEFINE_TRACE(UnderlyingSourceBase)
 {
+    ActiveDOMObject::trace(visitor);
     visitor->trace(m_controller);
-    ContextLifecycleObserver::trace(visitor);
 }
 
 } // namespace blink