Subject .mm files to the header sorting presubmit

chrome/browser/local_discovery/service_discovery_client_mac_unittest.mm

 // Copyright 2013 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 <Cocoa/Cocoa.h>
 
 #include "base/bind.h"
 #include "base/mac/scoped_nsobject.h"
 #include "base/message_loop/message_loop.h"
-#include "chrome/common/local_discovery/service_discovery_client.h"
 #include "chrome/browser/local_discovery/service_discovery_client_mac.h"
 #import "chrome/browser/ui/cocoa/cocoa_test_helper.h"
+#include "chrome/common/local_discovery/service_discovery_client.h"
 #include "testing/gtest_mac.h"
 
 @interface TestNSNetService : NSNetService {
  @private
   NSData* data_;
 }
 - (id) initWithData:(NSData *)data;
 @end
 
 @implementation TestNSNetService
@@ skipping 99 matching lines @@
   resolver_impl->GetContainerForTesting()->OnResolveUpdate(
       ServiceResolver::STATUS_SUCCESS);
 
   base::MessageLoop::current()->RunUntilIdle();
 
   EXPECT_EQ(1, num_resolves_);
   EXPECT_EQ(2u, last_service_description_.metadata.size());
 }
 
 }  // namespace local_discovery