Added HistoryService::GetHistoryCount() and helper functions in components/history

components/history/core/browser/history_types.h

 // Copyright 2014 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 COMPONENTS_HISTORY_CORE_BROWSER_HISTORY_TYPES_H_
 #define COMPONENTS_HISTORY_CORE_BROWSER_HISTORY_TYPES_H_
 
 #include <deque>
 #include <map>
 #include <set>
@@ skipping 434 matching lines @@
  private:
   friend class base::RefCountedThreadSafe<MostVisitedThumbnails>;
   virtual ~MostVisitedThumbnails();
 
   DISALLOW_COPY_AND_ASSIGN(MostVisitedThumbnails);
 };
 
 // Map from host to visit count, sorted by visit count descending.
 typedef std::vector<std::pair<std::string, int>> TopHostsList;
 
+// Statistics -----------------------------------------------------------------
+
+// HistoryCountResult encapsulates the result of a call to
+// HistoryBackend::GetHistoryCount.
+struct HistoryCountResult {
+  // Indicates whether the call to HistoryBackend::GetHistoryCount was
+  // successful or not. If false, then |count| is undefined.
+  bool success;
+  int count;
+};
+
 // Favicons -------------------------------------------------------------------
 
 // Used for the mapping between the page and icon.
 struct IconMapping {
   IconMapping();
   ~IconMapping();
 
   // The unique id of the mapping.
   IconMappingID mapping_id;
 
@@ skipping 55 matching lines @@
   void SetTimeRangeForOneDay(base::Time time);
 
   std::set<GURL> urls;
   base::Time begin_time;
   base::Time end_time;
 };
 
 }  // namespace history
 
 #endif  // COMPONENTS_HISTORY_CORE_BROWSER_HISTORY_TYPES_H_