Add field to monitor last visited time for each search engine

components/search_engines/default_search_manager.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_DEFAULT_SEARCH_MANAGER_H_
 #define COMPONENTS_SEARCH_ENGINES_DEFAULT_SEARCH_MANAGER_H_
 
 #include <memory>
 
 #include "base/callback.h"
@@ skipping 35 matching lines @@
   static const char kSearchURLPostParams[];
   static const char kSuggestionsURLPostParams[];
   static const char kInstantURLPostParams[];
   static const char kImageURLPostParams[];
 
   static const char kSafeForAutoReplace[];
   static const char kInputEncodings[];
 
   static const char kDateCreated[];
   static const char kLastModified[];
+  static const char kLastVisited[];
 
   static const char kUsageCount[];
   static const char kAlternateURLs[];
   static const char kSearchTermsReplacementKey[];
   static const char kCreatedByPolicy[];
   static const char kDisabledByPolicy[];
 
   enum Source {
     FROM_FALLBACK = 0,
     FROM_USER,
@@ skipping 90 matching lines @@
   // prefs). This will be null if no value was set in the pref store.
   std::unique_ptr<TemplateURLData> prefs_default_search_;
 
   // True if the default search is currently enforced by policy.
   bool default_search_controlled_by_policy_;
 
   DISALLOW_COPY_AND_ASSIGN(DefaultSearchManager);
 };
 
 #endif  // COMPONENTS_SEARCH_ENGINES_DEFAULT_SEARCH_MANAGER_H_