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

chrome/browser/resources/managed_user_passphrase_dialog.css

Index: chrome/browser/resources/managed_user_passphrase_dialog.css
diff --git a/chrome/browser/resources/managed_user_passphrase_dialog.css b/chrome/browser/resources/managed_user_passphrase_dialog.css
new file mode 100644
index 0000000000000000000000000000000000000000..1b255f0bf6e61ce1523364f19134ed9dcc2f8c32
--- /dev/null
+++ b/chrome/browser/resources/managed_user_passphrase_dialog.css
@@ -0,0 +1,32 @@
+/* Copyright (c) 2012 The Chromium Authors. All rights reserved.

[James Hawkins, 2013/02/06 17:06:41]

nit: It's not 2012 anymore.

+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file. */
+
+#managed-mode-passphrase-page {
+  min-width: 350px;
+}
+
+#managed-user-logo {
+  background-image: url('managed_user.png');
+  height: 68px;
+  width: 65px;
+}
+
+#instructions,
+#entry,
+#incorrect-passphrase-warning {
+  padding: 5px 15px;
+}
+
+#unlock {
+  float: right;
+}
+
+#buttons {
+  padding: 15px 15px;
+}
+
+#incorrect-passphrase-warning {
+  color: red;
+  font-weight: bold;
+}