Progressively refacto FirstRun class to first_run namespace(part 4).

chrome/browser/ui/cocoa/first_run_dialog.mm

Index: chrome/browser/ui/cocoa/first_run_dialog.mm
diff --git a/chrome/browser/ui/cocoa/first_run_dialog.mm b/chrome/browser/ui/cocoa/first_run_dialog.mm
index 6db75239000cab8f8e456c6c38a31c6093efdcba..6bbbc8ab9841a6a058a24a5a3ce89c367cb27879 100644
--- a/chrome/browser/ui/cocoa/first_run_dialog.mm
+++ b/chrome/browser/ui/cocoa/first_run_dialog.mm
@@ -152,7 +152,7 @@ void ShowFirstRunDialog(Profile* profile,
   // If the default search is not managed via policy, ask the user to
   // choose a default.
   TemplateURLService* model = TemplateURLServiceFactory::GetForProfile(profile);
-  if (FirstRun::ShouldShowSearchEngineSelector(model)) {
+  if (first_run::ShouldShowSearchEngineSelector(model)) {
     ShowSearchEngineSelectionDialog(profile,
                                     randomize_search_engine_experiment);
   }