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

Source/platform/LifecycleObserver.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 38 matching lines @@
         DOMWindowLifecycleObserverType
     };
 
     explicit LifecycleObserver(Context* context, Type type = GenericType)
         : m_lifecycleContext(nullptr)
         , m_observerType(type)
     {
 #if ENABLE(OILPAN)
         ThreadState::current()->registerPreFinalizer(*this);
 #endif
-        setContext(context);
+        observeContext(context);
     }
     virtual ~LifecycleObserver()
     {
 #if !ENABLE(OILPAN)
         dispose();
 #endif
     }
 
     virtual void trace(Visitor* visitor)
     {
         visitor->trace(m_lifecycleContext);
     }
     virtual void contextDestroyed() { }
     void dispose()
     {
-        setContext(nullptr);
+        observeContext(nullptr);
     }
 
     Context* lifecycleContext() const { return m_lifecycleContext; }
     void clearLifecycleContext() { m_lifecycleContext = nullptr; }
     Type observerType() const { return m_observerType; }
 
 protected:
-    void setContext(Context*);
+    void observeContext(Context*);
 
     RawPtrWillBeWeakMember<Context> m_lifecycleContext;
     Type m_observerType;
 };
 
 //
 // These functions should be specialized for each LifecycleObserver instances.
 //
-template<typename T> void observeContext(T*, LifecycleObserver<T>*) { ASSERT_NOT_REACHED(); }
-template<typename T> void unobserveContext(T*, LifecycleObserver<T>*) { ASSERT_NOT_REACHED(); }
+template<typename T> void observerContext(T*, LifecycleObserver<T>*) { ASSERT_NOT_REACHED(); }
+template<typename T> void unobserverContext(T*, LifecycleObserver<T>*) { ASSERT_NOT_REACHED(); }
 
 
 template<typename T>
-inline void LifecycleObserver<T>::setContext(typename LifecycleObserver<T>::Context* context)
+inline void LifecycleObserver<T>::observeContext(typename LifecycleObserver<T>::Context* context)
 {
     if (m_lifecycleContext)
-        unobserveContext(m_lifecycleContext.get(), this);
+        unobserverContext(m_lifecycleContext.get(), this);
 
     m_lifecycleContext = context;
 
     if (m_lifecycleContext)
-        observeContext(m_lifecycleContext.get(), this);
+        observerContext(m_lifecycleContext.get(), this);
 }
 
 } // namespace blink
 
 #endif // LifecycleObserver_h