Use process_singleton_linux on Mac.

base/process/process_handle.h

 // Copyright (c) 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.
 
 #ifndef BASE_PROCESS_PROCESS_HANDLE_H_
 #define BASE_PROCESS_PROCESS_HANDLE_H_
 
 #include "base/base_export.h"
 #include "base/basictypes.h"
 #include "base/files/file_path.h"
@@ skipping 63 matching lines @@
   MEDIUM_INTEGRITY,
   HIGH_INTEGRITY,
 };
 // Determine the integrity level of the specified process. Returns false
 // if the system does not support integrity levels (pre-Vista) or in the case
 // of an underlying system failure.
 BASE_EXPORT bool GetProcessIntegrityLevel(ProcessHandle process,
                                           IntegrityLevel* level);
 #endif
 
-#if defined(OS_LINUX) || defined(OS_ANDROID) || defined(OS_BSD)
+#if defined(OS_POSIX)
 // Returns the path to the executable of the given process.
 BASE_EXPORT FilePath GetProcessExecutablePath(ProcessHandle process);
-#endif
 
-#if defined(OS_POSIX)
 // Returns the ID for the parent of the given process.
 BASE_EXPORT ProcessId GetParentProcessId(ProcessHandle process);
 #endif
 
 }  // namespace base
 
 #endif  // BASE_PROCESS_PROCESS_HANDLE_H_