Add field to monitor last visited time for each search engine

components/search_engines/template_url_fetcher.cc

Index: components/search_engines/template_url_fetcher.cc
diff --git a/components/search_engines/template_url_fetcher.cc b/components/search_engines/template_url_fetcher.cc
index cf972d0eeb915643151d183a8757c22f6fabeb78..1edc22d5601c0ef1458aee617b18994fb0eb416a 100644
--- a/components/search_engines/template_url_fetcher.cc
+++ b/components/search_engines/template_url_fetcher.cc
@@ -149,6 +149,7 @@ void TemplateURLFetcher::RequestDelegate::AddSearchProvider() {
   TemplateURL* existing_url = NULL;
   if (!model->CanAddAutogeneratedKeyword(keyword_, GURL(template_url_->url()),
                                          &existing_url)) {
+    model->UpdateTemplateURLVisitTime(existing_url);

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

I don't think the changes in this file are the right place to update the
last_visited time.

Basically, these changes will update the time whenever we would have re-fetched
the TemplateURL.  But I think we want to update instead whenever there's a
history visit that matches the template_url in question.  To implement this,
you'd want to instead modify
TemplateURLService::UpdateKeywordSearchTermsForURL() to update the timestamp.

Behavioral differences, assuming some site like search_engine.com that has a
page with an OSDD and a search box, and a search results page with no OSDD:
* The existing patch would mark search_engine visited if the user navigates to
search_engine.com and then closes the tab; my proposal does not
* The existing patch would not mark search_engine visited if the user uses
search_engine directly from the omnibox; my patch would
* The existing patch would not mark search_engine visited if the user navigates
directly to a search results page on search_engine; my patch would

The second and third bullets above definitely seem like things we should change.
 The first is more arguable, but I would claim the user hasn't actually "used"
search_engine in this case.

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

Thanks for the info, Peter. Originally I was trying to implement in that way but
had no idea this function existed. Modifying
TemplateURLService::UpdateKeywordSearchTermsForURL() is definitely better than
my current implementation.

     fetcher_->RequestCompleted(this);  // WARNING: Deletes us!
     return;
   }
@@ -201,11 +202,13 @@ void TemplateURLFetcher::ScheduleDownload(
     return;
   }
 
-  const TemplateURL* template_url =
+  TemplateURL* template_url =
       template_url_service_->GetTemplateURLForKeyword(keyword);
   if (template_url && (!template_url->safe_for_autoreplace() ||
-                       template_url->originating_url() == osdd_url))
+                       template_url->originating_url() == osdd_url)) {
+    template_url_service_->UpdateTemplateURLVisitTime(template_url);
     return;
+  }
 
   // Make sure we aren't already downloading this request.
   for (const auto& request : requests_) {