Add a lock to the managed user settings page and require authentication for unlocking.

chrome/browser/managed_mode/managed_user_passphrase.h

+// 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.
+
+#ifndef CHROME_BROWSER_MANAGED_MODE_MANAGED_USER_PASSPHRASE_H_
+#define CHROME_BROWSER_MANAGED_MODE_MANAGED_USER_PASSPHRASE_H_
+
+#include <string>
+
+#include "base/basictypes.h"
+
+class ManagedUserPassphrase {

[Pam (message me for reviews), 2013/01/07 14:51:49]

Please add a brief class comment describing what this thing is. I know it seems
obvious from the name, but five years from now, when nobody's changed managed
mode for three years, some new developer may come along and not be familiar with
it at all.

+ public:
+  static void GenerateHashFromPassphrase(const std::string& passphrase,

[Pam (message me for reviews), 2013/01/07 14:51:49]

Please add a function comment describing what this does and what its arguments
are expected to be.

+      std::string* encoded_passphrase_hash);

[Bernhard Bauer, 2013/01/07 14:20:22]

Please add some newlines here. At least before the private section, and between
different types of declarations.

+ private:
+  static void GetPassphraseHash(const std::string& passphrase,

[Bernhard Bauer, 2013/01/07 14:20:22]

You might want to change the interface to one method that a creates a random
salt and a new hash with it and returns both, and one that checks a given
passphrase, salt and hash and returns whether they match. Dunno :)

+      std::string* passphrase_hash);

[Pam (message me for reviews), 2013/01/07 14:51:49]

std::string is pretty lightweight, and actually OK to just pass back by value.
This way is OK too, if you prefer it or it makes the API easier.

+  static const std::string kSalt_;

[Bernhard Bauer, 2013/01/07 14:20:22]

As a rule of thumb, static and private should trigger a warning flag. If it's
not a member and can't be accessed from the outside, you can usually declare it
in an anonymous namespace in the .cc file.

+  ManagedUserPassphrase();

[Bernhard Bauer, 2013/01/07 14:20:22]

See
http://google-styleguide.googlecode.com/svn/trunk/cppguide.xml#Declaration_Order
for the right order.

[Bernhard Bauer, 2013/01/07 14:20:22]

I think at the moment there is no need for a constructor, as the class has no
(non-static) members. If you don't plan to add members, you could think about
making it a namespace instead.

+  ~ManagedUserPassphrase();

[Pam (message me for reviews), 2013/01/07 14:51:49]

As a style point, I normally expect to see the constructor and destructor first
in the list, even before static member functions. Also, there should be a blank
line before the "public" section.

+  DISALLOW_COPY_AND_ASSIGN(ManagedUserPassphrase);
+};
+
+#endif  // CHROME_BROWSER_MANAGED_MODE_MANAGED_USER_PASSPHRASE_H_