Use process_singleton_linux on Mac.

base/process/process_handle_mac.cc

 // 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.
 
 #include "base/process/process_handle.h"
 
+#include <libproc.h>
 #include <sys/sysctl.h>
 #include <sys/types.h>
 
 #include "base/logging.h"
 
 namespace base {
 
 ProcessId GetParentProcessId(ProcessHandle process) {
   struct kinfo_proc info;
   size_t length = sizeof(struct kinfo_proc);
   int mib[4] = { CTL_KERN, KERN_PROC, KERN_PROC_PID, process };
   if (sysctl(mib, 4, &info, &length, NULL, 0) < 0) {
     DPLOG(ERROR) << "sysctl";
     return -1;
   }
   if (length == 0)
     return -1;
   return info.kp_eproc.e_ppid;
 }
 
+FilePath GetProcessExecutablePath(ProcessHandle process) {
+  char pathbuf[PROC_PIDPATHINFO_MAXSIZE];
+  if (!proc_pidpath(process, pathbuf, sizeof(pathbuf)))
+    return FilePath();
+
+  return FilePath(pathbuf);
+}
+
 }  // namespace base