Some first_run code cleanups (extracted from https://codereview.chromium.org/12670013 to keep that …

chrome/browser/first_run/first_run_mac.mm

Index: chrome/browser/first_run/first_run_mac.mm
diff --git a/chrome/browser/first_run/first_run_mac.mm b/chrome/browser/first_run/first_run_mac.mm
index cd6ecc66bb5c643a63b77737ea6b5fa720fd8d28..543d3d568578002cdff8b4824b622e61c25fb386 100644
--- a/chrome/browser/first_run/first_run_mac.mm
+++ b/chrome/browser/first_run/first_run_mac.mm
@@ -20,13 +20,9 @@ bool ImportBookmarks(const base::FilePath& import_bookmarks_path) {
   return false;
 }
 
-}  // namespace internal
-}  // namespace first_run
-
-namespace first_run {
-
 base::FilePath MasterPrefsPath() {
   return master_prefs::MasterPrefsPath();
 }
 
-}  //namespace first_run
+}  // namespace internal
+}  // namespace first_run