[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..1b9e32b53dc4da4298b6fd4c065819b311132c9e 100644
--- a/components/search_engines/template_url_service.h
+++ b/components/search_engines/template_url_service.h
@@ -133,11 +133,15 @@ class TemplateURLService : public WebDataServiceConsumer,
                                   const GURL& url,
                                   TemplateURL** template_url_to_replace);
 
-  // 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
-  // engine, separately from a full list of all TemplateURLs (which might be
-  // very long).
+  // Retruns whether |template_url| should be shown in the list of engines

[Peter Kasting, 2016/11/29 03:32:19]

Nit: Typo

[ltian, 2016/11/30 06:36:17]

Done.

+  // most likely to be selected as a default engine. This includes all
+  // prepopulated engines and engines created by policy.
+  bool ShowInPrepopulatedList(const TemplateURL* template_url);
+
+  // Returns whether |template_url| is the current default or return true for
+  // ShowInPrepopulatedList(). This is meant to highlight the current default,
+  // as well as the other most likely choices of default engine, separately
+  // from a full list of all TemplateURLs (which might be very long).

[Peter Kasting, 2016/11/29 03:32:19]

These comments are still confusingly overlapping.

What about this for the function comment and name for the new function you're
adding?  With this, I think the ShowInDefaultList() comment doesn't need a
change at all.

// Returns whether the engine is a "pre-existing" engine, either from the
// prepopulate list or created by policy.
bool IsPrepopulatedOrCreatedByPolicy(...);

[ltian, 2016/11/30 06:36:17]

Done.

   bool ShowInDefaultList(const TemplateURL* template_url);
 
   // Adds to |matches| all TemplateURLs whose keywords begin with |prefix|,