Set site engagement timestamps to privacy-respectful values when history is cleared.

components/history/core/browser/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 COMPONENTS_HISTORY_CORE_BROWSER_HISTORY_BACKEND_H_
 #define COMPONENTS_HISTORY_CORE_BROWSER_HISTORY_BACKEND_H_
 
 #include <stddef.h>
 #include <stdint.h>
 
@@ skipping 195 matching lines @@
   void ClearCachedDataForContextID(ContextID context_id);
 
   // Computes the |num_hosts| most-visited hostnames in the past 30 days. See
   // history_service.h for details. Returns an empty list if db_ is not
   // initialized.
   //
   // As a side effect, caches the list of top hosts for the purposes of
   // generating internal metrics.
   TopHostsList TopHosts(size_t num_hosts) const;
 
-  // Gets the counts of URLs that belong to |origins| in the history database.
-  // Origins that are not in the history database will be in the map with a
-  // count of 0.
+  // Gets the counts and last last time of URLs that belong to |origins| in the
+  // history database. Origins that are not in the history database will be in
+  // the map with a count and time of 0.
   // Returns an empty map if db_ is not initialized.
-  OriginCountMap GetCountsForOrigins(const std::set<GURL>& origins) const;
+  OriginCountAndLastVisitMap GetCountsAndLastVisitForOrigins(
+      const std::set<GURL>& origins) const;
 
   // Returns, for the given URL, a 0-based index into the list produced by
   // TopHosts(), corresponding to that URL's host. If TopHosts() has not
   // previously been run, or the host is not in the top kMaxTopHosts, returns
   // kMaxTopHosts.
   int HostRankIfAvailable(const GURL& url) const;
 
   // Navigation ----------------------------------------------------------------
 
   // |request.time| must be unique with high probability.
@@ skipping 319 matching lines @@
                            UpdateFaviconMappingsAndFetchNoDB);
   FRIEND_TEST_ALL_PREFIXES(HistoryBackendTest, QueryFilteredURLs);
   FRIEND_TEST_ALL_PREFIXES(HistoryBackendTest, TopHosts);
   FRIEND_TEST_ALL_PREFIXES(HistoryBackendTest, TopHosts_ElidePortAndScheme);
   FRIEND_TEST_ALL_PREFIXES(HistoryBackendTest, TopHosts_ElideWWW);
   FRIEND_TEST_ALL_PREFIXES(HistoryBackendTest, TopHosts_OnlyLast30Days);
   FRIEND_TEST_ALL_PREFIXES(HistoryBackendTest, TopHosts_MaxNumHosts);
   FRIEND_TEST_ALL_PREFIXES(HistoryBackendTest, TopHosts_IgnoreUnusualURLs);
   FRIEND_TEST_ALL_PREFIXES(HistoryBackendTest, HostRankIfAvailable);
   FRIEND_TEST_ALL_PREFIXES(HistoryBackendTest, RecordTopHostsMetrics);
-  FRIEND_TEST_ALL_PREFIXES(HistoryBackendTest, GetCountsForOrigins);
+  FRIEND_TEST_ALL_PREFIXES(HistoryBackendTest, GetCountsAndLastVisitForOrigins);
   FRIEND_TEST_ALL_PREFIXES(HistoryBackendTest, UpdateVisitDuration);
   FRIEND_TEST_ALL_PREFIXES(HistoryBackendTest, ExpireHistoryForTimes);
   FRIEND_TEST_ALL_PREFIXES(HistoryBackendTest, DeleteFTSIndexDatabases);
   FRIEND_TEST_ALL_PREFIXES(ProfileSyncServiceTypedUrlTest,
                            ProcessUserChangeRemove);
   friend class ::TestingProfile;
 
   // Computes the name of the specified database on disk.
   base::FilePath GetThumbnailFileName() const;
 
@@ skipping 316 matching lines @@
 
   // List of observers
   base::ObserverList<HistoryBackendObserver> observers_;
 
   DISALLOW_COPY_AND_ASSIGN(HistoryBackend);
 };
 
 }  // namespace history
 
 #endif  // COMPONENTS_HISTORY_CORE_BROWSER_HISTORY_BACKEND_H_