Closing a window requires closing web contents now.

In this way, we can prevent the close of window by using beforeunload
handler.

common/platform_util.h

@@ -30,6 +30,6 @@ void MoveItemToTrash(const base::FilePath& full_path);
 
 void Beep();
 
-}  // platform_util
+}  // namespace platform_util
 
 #endif  // ATOM_COMMON_PLATFORM_UTIL_H_