Add field to monitor last visited time for each search engine

components/search_engines/template_url_data.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_TEMPLATE_URL_DATA_H_
 #define COMPONENTS_SEARCH_ENGINES_TEMPLATE_URL_DATA_H_
 
 #include <string>
 #include <vector>
 
@@ skipping 64 matching lines @@
   //
   // NOTE: this may be 0, which indicates the TemplateURL was created before we
   // started tracking creation time.
   base::Time date_created;
 
   // The last time this TemplateURL was modified by a user, since creation.
   //
   // NOTE: Like date_created above, this may be 0.
   base::Time last_modified;
 
+  // Date when this TemplateURL was last visited.
+  //
+  // NOTE: Like data_created above, this may be 0.

[Peter Kasting, 2016/11/21 03:35:08]

Nit: I'd change this to "NOTE: This may be 0 if the URL has never been visited."

See also comment in .cc file.

[ltian, 2016/11/28 22:08:02]

Done.

+  base::Time last_visited;
+
   // True if this TemplateURL was automatically created by the administrator via
   // group policy.
   bool created_by_policy;
 
   // Number of times this TemplateURL has been explicitly used to load a URL.
   // We don't increment this for uses as the "default search engine" since
   // that's not really "explicit" usage and incrementing would result in pinning
   // the user's default search engine(s) to the top of the list of searches on
   // the New Tab page, de-emphasizing the omnibox as "where you go to search".
   int usage_count;
@@ skipping 15 matching lines @@
 
  private:
   // Private so we can enforce using the setters and thus enforce that these
   // fields are never empty.
   base::string16 short_name_;
   base::string16 keyword_;
   std::string url_;
 };
 
 #endif  // COMPONENTS_SEARCH_ENGINES_TEMPLATE_URL_DATA_H_