Simplify lifecycle notifiers and observers.

Source/core/dom/DocumentLifecycleObserver.cpp

 /*
  * 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
@@ skipping 14 matching lines @@
 
 
 #include "config.h"
 #include "core/dom/DocumentLifecycleObserver.h"
 
 #include "core/dom/Document.h"
 #include "core/dom/DocumentLifecycleNotifier.h"
 
 namespace blink {
 
-template<> void observeContext(Document* context, LifecycleObserver<Document>* observer)
+DocumentLifecycleObserver::DocumentLifecycleObserver(Document* document)
+    : LifecycleObserver<Document, DocumentLifecycleObserver, DocumentLifecycleNotifier>(document)
 {
-    static_cast<DocumentLifecycleNotifier*>(context)->addObserver(observer);
-}
-
-template<> void unobserveContext(Document* context, LifecycleObserver<Document>* observer)
-{
-    static_cast<DocumentLifecycleNotifier*>(context)->removeObserver(observer);
-}
-
-DocumentLifecycleObserver::DocumentLifecycleObserver(Document* document)
-    : LifecycleObserver<Document>(document, DocumentLifecycleObserverType)
-{
+    setContext(document);
 }
 
 DocumentLifecycleObserver::~DocumentLifecycleObserver()
 {
 }
 
 } // namespace blink