Remove LifecycleNotifier<>::m_context.

Source/core/dom/ContextLifecycleObserver.h

 /*
  * Copyright (C) 2008 Apple 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
@@ skipping 10 matching lines @@
  * 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 ContextLifecycleObserver_h
 #define ContextLifecycleObserver_h
 
 #include "core/dom/ExecutionContext.h"
+#include "platform/LifecycleObserver.h"
 
 namespace blink {
 
 class ContextLifecycleNotifier;
 
 class ContextLifecycleObserver : public LifecycleObserver<ExecutionContext, ContextLifecycleObserver, ContextLifecycleNotifier> {
 public:
     ExecutionContext* executionContext() const { return lifecycleContext(); }
 
     enum Type {
         GenericType,
         ActiveDOMObjectType,
     };
 
     Type observerType() const { return m_observerType; }
 
 protected:
     explicit ContextLifecycleObserver(ExecutionContext*, Type = GenericType);
 
     virtual ~ContextLifecycleObserver();
 
 private:
     Type m_observerType;
 };
 
 } // namespace blink
 
 #endif // ContextLifecycleObserver_h