Data from the autocomplete predictor wasn't deleted immediately when deleting browsing history.

chrome/browser/predictors/autocomplete_action_predictor.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_PREDICTORS_AUTOCOMPLETE_ACTION_PREDICTOR_H_
 #define CHROME_BROWSER_PREDICTORS_AUTOCOMPLETE_ACTION_PREDICTOR_H_
 
 #include <map>
 #include <memory>
 #include <tuple>
@@ skipping 169 matching lines @@
     const AutocompleteActionPredictorTable::Rows& rows_to_add,
     const AutocompleteActionPredictorTable::Rows& rows_to_update);
 
   // Called to populate the local caches. This also calls DeleteOldEntries
   // if the history service is available, or registers for the notification of
   // it becoming available.
   void CreateCaches(
       std::vector<AutocompleteActionPredictorTable::Row>* row_buffer);
 
   // Attempts to call DeleteOldEntries if the in-memory database has been loaded
-  // by |service|. Returns success as a boolean.
-  bool TryDeleteOldEntries(history::HistoryService* service);
+  // by |service|.
+  void TryDeleteOldEntries(history::HistoryService* service);
 
   // Called to delete any old or invalid entries from the database. Called after
   // the local caches are created once the history service is available.
   void DeleteOldEntries(history::URLDatabase* url_db);
 
   // Deletes any old or invalid entries from the local caches. |url_db| and
   // |id_list| must not be NULL. Every row id deleted will be added to id_list.
   void DeleteOldIdsFromCaches(
       history::URLDatabase* url_db,
       std::vector<AutocompleteActionPredictorTable::Row::Id>* id_list);
@@ skipping 61 matching lines @@
 
   ScopedObserver<history::HistoryService, history::HistoryServiceObserver>
       history_service_observer_;
 
   DISALLOW_COPY_AND_ASSIGN(AutocompleteActionPredictor);
 };
 
 }  // namespace predictors
 
 #endif  // CHROME_BROWSER_PREDICTORS_AUTOCOMPLETE_ACTION_PREDICTOR_H_