Revert r189385 "Remove LifecycleContext" and r189391, r189530, r189456 that block it

Source/core/frame/DOMWindowLifecycleNotifier.h

 /*
  * Copyright (C) 2013 Google Inc. All Rights Reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
  *    documentation and/or other materials provided with the distribution.
  *
  * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
  * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE INC. OR
  * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
  * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
  * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
 #ifndef DOMWindowLifecycleNotifier_h
 #define DOMWindowLifecycleNotifier_h
 
+#include "core/frame/DOMWindowLifecycleObserver.h"
+#include "core/frame/LocalDOMWindow.h"
 #include "platform/LifecycleNotifier.h"
-#include "wtf/HashSet.h"
 #include "wtf/PassOwnPtr.h"
 #include "wtf/TemporaryChange.h"
 #include "wtf/text/WTFString.h"
 
 namespace blink {
 
-class DOMWindowLifecycleObserver;
-class LocalDOMWindow;
+class DOMWindowLifecycleNotifier final : public LifecycleNotifier<LocalDOMWindow> {
+public:
+    static PassOwnPtr<DOMWindowLifecycleNotifier> create(LocalDOMWindow*);
 
-class DOMWindowLifecycleNotifier : public LifecycleNotifier<LocalDOMWindow> {
-public:
     void notifyAddEventListener(LocalDOMWindow*, const AtomicString& eventType);
     void notifyRemoveEventListener(LocalDOMWindow*, const AtomicString& eventType);
     void notifyRemoveAllEventListeners(LocalDOMWindow*);
 
     virtual void addObserver(Observer*) override;
     virtual void removeObserver(Observer*) override;
 
-protected:
+private:
     explicit DOMWindowLifecycleNotifier(LocalDOMWindow*);
 
-private:
     typedef HashSet<DOMWindowLifecycleObserver*> DOMWindowObserverSet;
     DOMWindowObserverSet m_windowObservers;
 };
 
 } // namespace blink
 
 #endif // DOMWindowLifecycleNotifier_h