Track fraction of visits to top URLs.

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 560 matching lines @@
 
   // Returns the name of the Favicons database. This is the new name
   // of the Thumbnails database.
   // See ThumbnailDatabase::RenameAndDropThumbnails.
   base::FilePath GetFaviconsFileName() const;
   base::FilePath GetArchivedFileName() const;
 
 #if defined(OS_ANDROID)
   // Returns the name of android cache database.
   base::FilePath GetAndroidCacheFileName() const;
+
+  // Populate a map from a |MostVisitedURLList|. The map assigns a rank to each
+  // top URL and its redirects. This should only be done once at backend
+  // initialization.
+  // This can be removed for M31. (See issue 248761.)
+
+  void PopulateMostVisitedURLMap();
+  // Record counts of page visits by rank. If a url is not ranked, record the
+  // page visit in a slot corresponding to |max_top_url_count|, which should
+  // be one greater than the largest rank of any url in |top_urls|.
+  // This can be removed for M31. (See issue 248761.)
+  void RecordTopPageVisitStats(const GURL& url);
 #endif
 
   class URLQuerier;
   friend class URLQuerier;
 
   // Does the work of Init.
   void InitImpl(const std::string& languages);
 
   // Closes all databases managed by HistoryBackend. Commits any pending
   // transactions.
@@ skipping 311 matching lines @@
   // loaded.
   BookmarkService* bookmark_service_;
 
   // Publishes the history to all indexers which are registered to receive
   // history data from us. Can be NULL if there are no listeners.
   scoped_ptr<HistoryPublisher> history_publisher_;
 
 #if defined(OS_ANDROID)
   // Used to provide the Android ContentProvider APIs.
   scoped_ptr<AndroidProviderBackend> android_provider_backend_;
+
+  // Used to provide UMA on the number of page visits that are to the most
+  // visited URLs. This is here because the backend both has access to this
+  // information and is notified of page visits. The top sites service should
+  // be used instead whenever possible.
+  std::map<GURL, int> most_visited_urls_map_;
 #endif
 
   // Used to manage syncing of the typed urls datatype. This will be NULL
   // before Init is called.
   scoped_ptr<TypedUrlSyncableService> typed_url_syncable_service_;
 
   DISALLOW_COPY_AND_ASSIGN(HistoryBackend);
 };
 
 }  // namespace history
 
 #endif  // CHROME_BROWSER_HISTORY_HISTORY_BACKEND_H_