Add field to monitor last visited time for each search engine

components/search_engines/keyword_table.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_SEARCH_ENGINES_KEYWORD_TABLE_H_
 #define COMPONENTS_SEARCH_ENGINES_KEYWORD_TABLE_H_
 
 #include <stdint.h>
 
 #include <string>
@@ skipping 113 matching lines @@
   int GetBuiltinKeywordVersion();
 
   // Returns a comma-separated list of the keyword columns for the current
   // version of the table.
   static std::string GetKeywordColumns();
 
   // Table migration functions.
   bool MigrateToVersion53AddNewTabURLColumn();
   bool MigrateToVersion59RemoveExtensionKeywords();
   bool MigrateToVersion68RemoveShowInDefaultListColumn();
+  bool MigrateToVersion69AddLastVisitedColumn();
 
  private:
   friend class KeywordTableTest;
   FRIEND_TEST_ALL_PREFIXES(WebDatabaseMigrationTest, MigrateVersion44ToCurrent);
 
   // NOTE: Since the table columns have changed in different versions, many
   // functions below take a |table_version| argument which dictates which
   // version number's column set to use.
 
   // Fills |data| with the data in |s|.  Returns false if we couldn't fill
@@ skipping 22 matching lines @@
                           std::string* result);
 
   // Migrates table |name| (which should be either "keywords" or
   // "keywords_backup") from version 44 to version 45.
   bool MigrateKeywordsTableForVersion45(const std::string& name);
 
   DISALLOW_COPY_AND_ASSIGN(KeywordTable);
 };
 
 #endif  // COMPONENTS_SEARCH_ENGINES_KEYWORD_TABLE_H_