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

Source/core/dom/ContextLifecycleNotifier.h

Index: Source/core/dom/ContextLifecycleNotifier.h
diff --git a/Source/core/dom/ContextLifecycleNotifier.h b/Source/core/dom/ContextLifecycleNotifier.h
index 178bf676ddc25d37917f03c261bbf2d8a4fd5fb1..03b3defecfc324148634fff074bd8b69fb87fece 100644
--- a/Source/core/dom/ContextLifecycleNotifier.h
+++ b/Source/core/dom/ContextLifecycleNotifier.h
@@ -24,10 +24,10 @@
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  *
  */
-
 #ifndef ContextLifecycleNotifier_h
 #define ContextLifecycleNotifier_h
 
+#include "core/dom/ExecutionContext.h"
 #include "platform/LifecycleNotifier.h"
 #include "wtf/HashSet.h"
 #include "wtf/PassOwnPtr.h"
@@ -35,10 +35,13 @@
 namespace blink {
 
 class ActiveDOMObject;
-class ExecutionContext;
 
 class ContextLifecycleNotifier : public LifecycleNotifier<ExecutionContext> {
 public:
+    static PassOwnPtr<ContextLifecycleNotifier> create(ExecutionContext*);
+
+    virtual ~ContextLifecycleNotifier();
+
     typedef HashSet<ActiveDOMObject*> ActiveDOMObjectSet;
 
     const ActiveDOMObjectSet& activeDOMObjects() const { return m_activeDOMObjects; }
@@ -60,6 +63,11 @@ private:
     ActiveDOMObjectSet m_activeDOMObjects;
 };
 
+inline PassOwnPtr<ContextLifecycleNotifier> ContextLifecycleNotifier::create(ExecutionContext* context)
+{
+    return adoptPtr(new ContextLifecycleNotifier(context));
+}
+
 } // namespace blink
 
 #endif // ContextLifecycleNotifier_h