Add field to monitor last visited time for each search engine

components/search_engines/template_url_service.h

Index: components/search_engines/template_url_service.h
diff --git a/components/search_engines/template_url_service.h b/components/search_engines/template_url_service.h
index 801ca6364295522dc093aff93e476256ab2f7a01..86d31c5b60ce9ccecc6d8629db544270918d390e 100644
--- a/components/search_engines/template_url_service.h
+++ b/components/search_engines/template_url_service.h
@@ -288,6 +288,9 @@ class TemplateURLService : public WebDataServiceConsumer,
   // prepopulate data.
   void RepairPrepopulatedSearchEngines();
 
+  // Updates the last_visited time of TemplateURL to the current time.
+  bool UpdateTemplateURLVisitTime(TemplateURL* url);

[Peter Kasting, 2016/12/01 07:38:25]

This is only public due to being used in a test.  I'm inclined to make it
private instead and FRIEND_TEST the test, as we don't really want any non-test
code calling this.

I don't understand why this function returns a value that no one ever reads.  I
think you must have misunderstood my request that you add an Update() function
that would do UpdateNoNotify() + NotifyObservers(), and instead thought I was
talking about this function, and you added a return value to it?  I'm very
confused, and just trying to go off how there's an extra return value here,
whereas there's no Update() (but maybe you intended to add that in a separate
cleanup patch, which would be fine).

[ltian, 2016/12/01 10:02:58]

Sorry I totally misunderstood of your thought. Will fix it.

+
   // Observers used to listen for changes to the model.
   // TemplateURLService does NOT delete the observers when deleted.
   void AddObserver(TemplateURLServiceObserver* observer);