Simplify lifecycle notifiers and observers.

Source/core/page/PageLifecycleObserver.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
@@ skipping 15 matching lines @@
 
 #ifndef PageLifecycleObserver_h
 #define PageLifecycleObserver_h
 
 #include "core/page/Page.h"
 #include "platform/LifecycleObserver.h"
 
 namespace blink {
 
 class LocalFrame;
+class PageLifecycleNotifier;
 
-template<> void observeContext(Page*, LifecycleObserver<Page>*);
-template<> void unobserveContext(Page*, LifecycleObserver<Page>*);
-
-class PageLifecycleObserver : public LifecycleObserver<Page> {
+class PageLifecycleObserver : public LifecycleObserver<Page, PageLifecycleObserver, PageLifecycleNotifier> {
 public:
-    explicit PageLifecycleObserver(Page*);
-    virtual ~PageLifecycleObserver();
+    virtual void pageVisibilityChanged() { }
+    virtual void didCommitLoad(LocalFrame*) { }
 
     Page* page() const;
 
-    virtual void pageVisibilityChanged() { }
-    virtual void didCommitLoad(LocalFrame*) { }
+protected:
+    explicit PageLifecycleObserver(Page*);
+    virtual ~PageLifecycleObserver();
 };
 
 } // namespace blink
 
 #endif // PageLifecycleObserver_h