Add a new function for getting a deterministic machine ID

chrome/browser/prefs/tracked/device_id.h

Index: chrome/browser/prefs/tracked/device_id.h
diff --git a/chrome/browser/prefs/tracked/device_id.h b/chrome/browser/prefs/tracked/device_id.h
new file mode 100644
index 0000000000000000000000000000000000000000..6ff57b88e0eb372c1051a65f05d77c6183b13089
--- /dev/null
+++ b/chrome/browser/prefs/tracked/device_id.h
@@ -0,0 +1,23 @@
+// Copyright 2015 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 CHROME_BROWSER_PREFS_TRACKED_DEVICE_ID_H_
+#define CHROME_BROWSER_PREFS_TRACKED_DEVICE_ID_H_
+
+#include <string>
+
+enum class MachineIdStatus {
+  SUCCESS = 0,
+  FAILURE,         // Returned if attempt to obtain a machine-specific ID fails.
+  NOT_IMPLEMENTED  // Returned if the method for obtaining a machine-specific ID
+                   // is not implemented for the system.
+};
+
+// Populates |machine_id| with a deterministic ID for this machine. |machine_id|
+// must not be null. Returns |FAILURE| if a machine ID cannot be obtained or
+// |NOT_IMPLEMENTED| on systems for which this feature is not supported (in both
+// cases |machine_id| is left untouched).
+MachineIdStatus GetDeterministicMachineSpecificId(std::string* machine_id);
+
+#endif  // CHROME_BROWSER_PREFS_TRACKED_DEVICE_ID_H_