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..c46edcf1a8c742f4f380b4da5a360eb50fb3c51f
--- /dev/null
+++ b/chrome/browser/prefs/tracked/device_id.h
@@ -0,0 +1,25 @@
+// 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

[grt (UTC plus 2), 2015/01/27 21:08:45]

wrap at 80 cols:
  NOT_IMPLEMENTED  // Returned if the method for obtaining a machine-specific ID
                   // is not implemented for the system.

[alito, 2015/01/29 23:25:48]

Done.

+                   // machine-specific ID is not implemented for
+                   // the system.
+};
+
+// Populates |machine_id| with a deterministic ID for this

[grt (UTC plus 2), 2015/01/27 21:08:45]

80 cols:
// 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).

[alito, 2015/01/29 23:25:48]

Done.

+// 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_