The check() method of StyleChecker subclasses are instance methods, while CommitChecker subclasses use class methods. This makes unified handling of checkers more complicated. Turn the StyleChecker check() method into a class method, passing it the contents to be checked directly. While at it, fix two style issues reported by checkstyle.py. Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>