Revert of Port HistoryService::GetVisibleVisitCountToHost to CancelableTaskTracker

chrome/browser/history/history_types.h

Index: chrome/browser/history/history_types.h
diff --git a/chrome/browser/history/history_types.h b/chrome/browser/history/history_types.h
index b0923c4e83fccecc458217c4ea9316e3b07de7e4..8a4e3f6d9d6d64a573fedc1965c5c4bb40a2b996 100644
--- a/chrome/browser/history/history_types.h
+++ b/chrome/browser/history/history_types.h
@@ -286,7 +286,7 @@
 
 // QueryURLResult -------------------------------------------------------------
 
-// QueryURLResult encapsulates the result of a call to HistoryBackend::QueryURL.
+// QueryURLResult encapsulate the result of a call to HistoryBackend::QueryURL.
 struct QueryURLResult {
   QueryURLResult();
   ~QueryURLResult();
@@ -296,19 +296,6 @@
   bool success;
   URLRow row;
   VisitVector visits;
-};
-
-// VisibleVisitCountToHostResult ----------------------------------------------
-
-// VisibleVisitCountToHostResult encapsulates the result of a call to
-// HistoryBackend::GetVisibleVisitCountToHost.
-struct VisibleVisitCountToHostResult {
-  // Indicates whether the call to HistoryBackend::GetVisibleVisitCountToHost
-  // was successfull or not. If false, then both |count| and |first_visit| are
-  // undefined.
-  bool success;
-  int count;
-  base::Time first_visit;
 };
 
 // MostVisitedURL --------------------------------------------------------------