Eliminate sending NOTIFICATION_TOP_SITES_* from TopSites

chrome/browser/history/top_sites.h

Index: chrome/browser/history/top_sites.h
diff --git a/chrome/browser/history/top_sites.h b/chrome/browser/history/top_sites.h
index 47ed7de8cfe4b78d75d2d05e6d687adafbeb744e..d8f9c298875c6d44a84b0b044721e91543296946 100644
--- a/chrome/browser/history/top_sites.h
+++ b/chrome/browser/history/top_sites.h
@@ -11,6 +11,7 @@
 #include "base/memory/ref_counted.h"
 #include "chrome/browser/history/history_service.h"
 #include "chrome/browser/history/history_types.h"
+#include "components/history/core/browser/top_sites_observer.h"
 #include "components/history/core/common/thumbnail_score.h"
 #include "third_party/skia/include/core/SkColor.h"
 #include "ui/gfx/image/image.h"
@@ -38,7 +39,7 @@ class TopSites
     : public base::RefCountedThreadSafe<TopSites>,
       public content::NotificationObserver {
  public:
-  TopSites() {}
+  TopSites();
 
   // Initializes TopSites.
   static TopSites* Create(Profile* profile, const base::FilePath& db_name);
@@ -167,10 +168,20 @@ class TopSites
     // The best color to highlight the page (should roughly match favicon).
     SkColor color;
   };
+
+  // Add Observer to the list.
+  void AddObserver(TopSitesObserver* observer);
+
+  // Remove Observer from the list.
+  void RemoveObserver(TopSitesObserver* observer);
+
  protected:
-  virtual ~TopSites() {}
+  void NotifyTopSitesLoaded();
+  void NotifyTopSitesChanged();
+  virtual ~TopSites();
 
  private:
+  ObserverList<TopSitesObserver> observer_list_;
   friend class base::RefCountedThreadSafe<TopSites>;
 };