Port History::QueryMostVisitedURLs to use CancelableTaskTracker

chrome/browser/history/history_backend.h

Index: chrome/browser/history/history_backend.h
diff --git a/chrome/browser/history/history_backend.h b/chrome/browser/history/history_backend.h
index 457e2d059208dbc8d13b955405caf919ff6b1f76..78fa3cd9001407c7cf79e3bd2f42ea5f0fa528c1 100644
--- a/chrome/browser/history/history_backend.h
+++ b/chrome/browser/history/history_backend.h
@@ -164,10 +164,9 @@ class HistoryBackend : public base::RefCountedThreadSafe<HistoryBackend>,
   // Request the |result_count| most visited URLs and the chain of
   // redirects leading to each of these URLs. |days_back| is the
   // number of days of history to use. Used by TopSites.
-  void QueryMostVisitedURLs(
-      scoped_refptr<QueryMostVisitedURLsRequest> request,
-      int result_count,
-      int days_back);
+  void QueryMostVisitedURLs(int result_count,
+                            int days_back,
+                            MostVisitedURLList* result);
 
   // Request the |result_count| URLs and the chain of redirects
   // leading to each of these URLs, filterd and sorted based on the |filter|.
@@ -178,11 +177,6 @@ class HistoryBackend : public base::RefCountedThreadSafe<HistoryBackend>,
       const history::VisitFilter& filter,
       bool debug);
 
-  // QueryMostVisitedURLs without the request.
-  void QueryMostVisitedURLsImpl(int result_count,
-                                int days_back,
-                                MostVisitedURLList* result);
-
   // Computes the most recent URL(s) that the given canonical URL has
   // redirected to and returns true on success. There may be more than one
   // redirect in a row, so this function will fill the given array with the