Added uma for pin unlock set up.

chrome/browser/resources/settings/people_page/lock_screen_constants.js

Index: chrome/browser/resources/settings/people_page/lock_screen_constants.js
diff --git a/chrome/browser/resources/settings/people_page/lock_screen_constants.js b/chrome/browser/resources/settings/people_page/lock_screen_constants.js
new file mode 100644
index 0000000000000000000000000000000000000000..039048572060102ad56087bdcd22ce472ddb6dd0
--- /dev/null
+++ b/chrome/browser/resources/settings/people_page/lock_screen_constants.js
@@ -0,0 +1,26 @@
+// Copyright 2016 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.
+
+/**
+ * @fileoverview Constants used for logging the pin unlock setup uma.
+ */
+
+/**
+ * Name of the pin unlock setup uma histogram.
+ * @type {string}
+ */
+var PinUnlockUmaHistogramName = 'Settings.PinUnlockSetup';

[jdufault, 2016/09/13 18:36:05]

Since you're already introducing a new file, what about adding a helper method

  recordLockScreenProgress(LockScreenProgress.START_SCREEN_LOCK);

[sammiequon, 2016/09/13 19:21:40]

Done.

+
+/**
+ * Stages the user can enter while setting up pin unlock.
+ * @enum {number}
+ */
+var PinUnlockSetupType = {

[jdufault, 2016/09/13 18:36:05]

Rename to LockScreenProgress?

[sammiequon, 2016/09/13 19:21:40]

Done.

+  START_SCREEN_LOCK: 0,
+  ENTER_PASSWORD_CORRECTLY: 1,
+  CHOOSE_PIN_OR_PASSWORD: 2,
+  ENTER_PIN: 3,
+  CONFIRM_PIN: 4,
+  MAX_BUCKET: 5
+};