[Android] Allow setting recently visited search engines as default 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..58970e4e59e926117b9d729584e858fca262d668 100644
--- a/components/search_engines/template_url_service.h
+++ b/components/search_engines/template_url_service.h
@@ -133,6 +133,10 @@ class TemplateURLService : public WebDataServiceConsumer,
                                   const GURL& url,
                                   TemplateURL** template_url_to_replace);
 
+  // Retruns whether |template_url| should be shown in the list of engines
+  // prepopulated by Chrome browser.

[Peter Kasting, 2016/11/23 21:30:27]

Nit: Typo + grammar

Because you are splitting the existing functionality of ShowInDefaultList() into
pieces, you should aim to split its comment into pieces as well.  All that stuff
about "most likely choices of default engine" probably belongs over here, and
the two function comments should be written to make it clear how one is a
superset of the other.

[ltian, 2016/11/29 02:44:03]

Done.

+  bool ShowInPrepopulatedList(const TemplateURL* template_url);
+
   // Returns whether |template_url| should be shown in the list of engines
   // most likely to be selected as a default engine. This is meant to highlight
   // the current default, as well as the other most likely choices of default