Subject .mm files to the header sorting presubmit

chrome/browser/ui/cocoa/new_tab_button.mm

 // Copyright (c) 2011 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #import "chrome/browser/ui/cocoa/new_tab_button.h"
+
 #import "chrome/browser/ui/cocoa/image_button_cell.h"
 #include "grit/theme_resources.h"
 #include "ui/base/resource/resource_bundle.h"
 
 // A simple override of the ImageButtonCell to disable handling of
 // -mouseEntered.
 @interface NewTabButtonCell : ImageButtonCell
 
 - (void)mouseEntered:(NSEvent*)theEvent;
 
@@ skipping 43 matching lines @@
 
 - (void)windowDidChangeTheme {
   [self setNeedsDisplay:YES];
 }
 
 - (void)windowDidChangeActive {
   [self setNeedsDisplay:YES];
 }
 
 @end