[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.h

Index: chrome/browser/search_engines/template_url_service_android.h
diff --git a/chrome/browser/search_engines/template_url_service_android.h b/chrome/browser/search_engines/template_url_service_android.h
index f140e5930718d98d4862f2e2367e5b29452b6154..4073105340423ecbe13ba9b1e9b0bb9b493b1b1c 100644
--- a/chrome/browser/search_engines/template_url_service_android.h
+++ b/chrome/browser/search_engines/template_url_service_android.h
@@ -89,9 +89,15 @@ class TemplateUrlServiceAndroid : public TemplateURLServiceObserver {
 
   // Updates |template_urls_| to contain all TemplateURLs.  It sorts this list
   // with prepopulated engines first, then any default non-prepopulated engine,
-  // then other non-prepopulated engines.
+  // then other non-prepopulated engines based on last_visited in descending
+  // order.
   void LoadTemplateURLs();
 
+  // Counts the number of custom search engine needed to be remove from
+  // |template_urls_|. Android only shows top 5 most recently visited engines,
+  // the rest of custom search engine will be removed from |template_urls_|.
+  int CountRemovedSearchEngineNum(std::vector<TemplateURL*>::iterator bound);
+
   JavaObjectWeakGlobalRef weak_java_obj_;
 
   // Pointer to the TemplateUrlService for the main profile.