Make TopSites a RefcountedKeyedService

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 6fa5826ca1d16f0172e54f3c31344a59b589516b..c27c1dce5749c22ccccbe2c5e34cb46283bbcd05 100644
--- a/chrome/browser/history/top_sites.h
+++ b/chrome/browser/history/top_sites.h
@@ -8,12 +8,12 @@
 #include "base/basictypes.h"
 #include "base/callback.h"
 #include "base/gtest_prod_util.h"
-#include "base/memory/ref_counted.h"
 #include "base/observer_list.h"
 #include "base/task/cancelable_task_tracker.h"
 #include "components/history/core/browser/history_types.h"
 #include "components/history/core/browser/top_sites_observer.h"
 #include "components/history/core/common/thumbnail_score.h"
+#include "components/keyed_service/core/refcounted_keyed_service.h"
 #include "content/public/browser/notification_observer.h"
 #include "third_party/skia/include/core/SkColor.h"
 #include "ui/gfx/image/image.h"
@@ -37,9 +37,8 @@ class TopSitesCache;
 //
 // Some methods should only be called from the UI thread (see method
 // descriptions below). All others are assumed to be threadsafe.
-class TopSites
-    : public base::RefCountedThreadSafe<TopSites>,
-      public content::NotificationObserver {
+class TopSites : public RefcountedKeyedService,
+                 public content::NotificationObserver {
  public:
   TopSites();
 
@@ -119,9 +118,6 @@ class TopSites
   // Clear the blacklist. Should be called from the UI thread.
   virtual void ClearBlacklistedURLs() = 0;
 
-  // Shuts down top sites.
-  virtual void Shutdown() = 0;
-
   // Query history service for the list of available thumbnails. Returns the
   // task id for the request, or |base::CancelableTaskTracker::kBadTaskId| if a
   // request could not be made. Public only for testing purposes.