[Android] Sort custom search engines based on last visited time and display only top 3 most recentl…

chrome/browser/search_engines/template_url_service_android.cc

Index: chrome/browser/search_engines/template_url_service_android.cc
diff --git a/chrome/browser/search_engines/template_url_service_android.cc b/chrome/browser/search_engines/template_url_service_android.cc
index 306cd44c2130303ba5a742eaabe1db46d58d08b0..bd669952364b2e8cd27f9e58c87f0b2f8088d95c 100644
--- a/chrome/browser/search_engines/template_url_service_android.cc
+++ b/chrome/browser/search_engines/template_url_service_android.cc
@@ -152,10 +152,27 @@ void TemplateUrlServiceAndroid::LoadTemplateURLs() {
     if (template_url_service_->IsPrepopulatedOrCreatedByPolicy(lhs)) {
       return !rhs_prepopulated ||
              (lhs->prepopulate_id() < rhs->prepopulate_id());
+    } else if (lhs == default_search_provider) {
+      return !rhs_prepopulated;
     }
-    return (lhs == default_search_provider && !rhs_prepopulated);
+    return rhs != default_search_provider && !rhs_prepopulated &&
+        lhs->last_visited().ToTimeT() > rhs->last_visited().ToTimeT();
   };
   std::sort(template_urls_.begin(), template_urls_.end(), comp);

[Peter Kasting, 2016/12/06 06:24:55]

The sort comparator is getting complicated.

I wonder if it would be better to use a couple of calls to std::partition() to
do this.  This would avoid the need to count the elements in the "recently
visited" list at all, since you would be able to compute the size of that
partition directly.  You would still need a sort() call for the first partition
in this case.

Or maybe a sort() with "prepopulated before non-prepopulated, sorted by ID",
followed by a partition() call.

[ltian, 2016/12/07 00:56:43]

Done.

+  int num_remove = CountRemovedSearchEngineNum();
+  template_urls_.erase(template_urls_.end()-num_remove,
+                       template_urls_.end());

[Peter Kasting, 2016/12/06 06:24:55]

Nit: Use resize()

[ltian, 2016/12/07 00:56:43]

Done.

+
+}
+
+int TemplateUrlServiceAndroid::CountRemovedSearchEngineNum() {
+  int num_custom_engine = 0;
+  for (std::vector<TemplateURL*>::const_iterator i = template_urls_.begin();
+      i != template_urls_.end(); i++) {
+    template_url_service_->ShowInDefaultList(*i) ? num_custom_engine :
+        num_custom_engine++;
+  }

[Peter Kasting, 2016/12/06 06:24:55]

Nit: Use std::count_if

[ltian, 2016/12/07 00:56:43]

Done.

+  return num_custom_engine > 5 ? num_custom_engine - 5 : 0;

[Peter Kasting, 2016/12/06 06:24:55]

Nit: Use std::max

[ltian, 2016/12/07 00:56:43]

Done.

 }
 
 void TemplateUrlServiceAndroid::OnTemplateURLServiceChanged() {