Move/replace/rename URL-based extension getters from ExtensionService to/in ExtensionSet.

chrome/browser/chromeos/login/help_app_launcher.cc

Index: chrome/browser/chromeos/login/help_app_launcher.cc
diff --git a/chrome/browser/chromeos/login/help_app_launcher.cc b/chrome/browser/chromeos/login/help_app_launcher.cc
index b3c95a7bdf6bbbfa10442f4b2e298e82224a2a12..0184147723d75dd854a1a4e8b8c2aa30d15ebcc6 100644
--- a/chrome/browser/chromeos/login/help_app_launcher.cc
+++ b/chrome/browser/chromeos/login/help_app_launcher.cc
@@ -46,7 +46,7 @@ void HelpAppLauncher::ShowHelpTopic(HelpTopic help_topic_id) {
                               static_cast<int>(help_topic_id)));
   // HelpApp component extension presents only in official builds so we can
   // show help only when the extensions is installed.
-  if (service->GetExtensionByURL(url))
+  if (service->extensions()->GetByID(url.host()))
     ShowHelpTopicDialog(GURL(url));
 }