Fix OS_MACOS typos. Should be OS_MACOSX.

chrome/browser/download/download_path_reservation_tracker_unittest.cc

 // Copyright (c) 2012 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.
 
 #include "base/file_util.h"
 #include "base/files/file_path.h"
 #include "base/files/scoped_temp_dir.h"
 #include "base/memory/weak_ptr.h"
 #include "base/message_loop.h"
 #include "base/observer_list.h"
@@ skipping 437 matching lines @@
   EXPECT_TRUE(IsPathInUse(new_target_path));
 
   // Destroying the item should release the reservation.
   item.reset();
   message_loop_.RunUntilIdle();
   EXPECT_FALSE(IsPathInUse(new_target_path));
 }
 
 // Tests for long name truncation. On other platforms automatic truncation
 // is not performed (yet).
-#if defined(OS_WIN) || defined(OS_MAC) || defined(OS_CHROMEOS)
+#if defined(OS_WIN) || defined(OS_MACOSX) || defined(OS_CHROMEOS)
 
 TEST_F(DownloadPathReservationTrackerTest, BasicTruncation) {
   int real_max_length =
       file_util::GetMaximumPathComponentLength(default_download_path());
   ASSERT_NE(-1, real_max_length);
 
   // TODO(kinaba): the current implementation leaves spaces for appending
   // ".crdownload". So take it into account. Should be removed in the future.
   const size_t max_length = real_max_length - 11;
 
@@ skipping 56 matching lines @@
   ASSERT_FALSE(IsPathInUse(path));
 
   base::FilePath reserved_path;
   bool verified = false;
   CallGetReservedPath(*item, path, false, &reserved_path, &verified);
   // We cannot truncate a path with very long extension.
   EXPECT_FALSE(verified);
 }
 
 #endif