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 891 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_;

[jar (doing other things), 2013/06/19 00:49:58]

nit: Making this a member is good/fine.  You should make the functions that
manipulate this into methods, and then you won't need to pass it in as an
argument.

[bengr, 2013/06/19 17:44:24]

Done.

 #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_