Port HistoryService::GetVisibleVisitCountToHost to CancelableTaskTracker

chrome/browser/history/history_backend.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CHROME_BROWSER_HISTORY_HISTORY_BACKEND_H_
 #define CHROME_BROWSER_HISTORY_HISTORY_BACKEND_H_
 
 #include <set>
 #include <string>
 #include <utility>
@@ skipping 151 matching lines @@
   // no redirects for the most recent visit of the URL, or the URL is not
   // in history, the array will be empty.
   void QueryRedirectsFrom(const GURL& url, RedirectList* redirects);
 
   // Similar to above function except computes a chain of redirects to the
   // given URL. Stores the most recent list of redirects ending at |url| in the
   // given RedirectList. For example, if we have the redirect list A -> B -> C,
   // then calling this function with url=C would fill redirects with {B, A}.
   void QueryRedirectsTo(const GURL& url, RedirectList* redirects);
 
-  void GetVisibleVisitCountToHost(
-      scoped_refptr<GetVisibleVisitCountToHostRequest> request,
-      const GURL& url);
+  void GetVisibleVisitCountToHost(const GURL& url,
+                                  VisibleVisitCountToHostResult* result);
 
   // 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(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|.
@@ skipping 652 matching lines @@
 
   // Listens for the system being under memory pressure.
   scoped_ptr<base::MemoryPressureListener> memory_pressure_listener_;
 
   DISALLOW_COPY_AND_ASSIGN(HistoryBackend);
 };
 
 }  // namespace history
 
 #endif  // CHROME_BROWSER_HISTORY_HISTORY_BACKEND_H_