Add the authenticate screen for the quick unlock settings.

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

+// 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.
+
+QuickUnlockScreen = {
+  AUTHENTICATE: 'quick-unlock-authenticate',
+  CHOOSE_METHOD: 'quick-unlock-choose-method',
+  SETUP_PIN: 'quick-unlock-setup-pin'
+};
+
+QuickUnlockRoutingBehavior = {
+  properties: {
+    currentRoute: {
+      type: Object,
+      notify: true,
+    }
+  },
+
+  /**
+   * Returns the QuickUnlockScreen type that is associated with this object.
+   */
+  screenType: function() {
+    console.error('Missing method definition');
+  },
+
+  /**
+   * Returns true if the given screen is active.
+   * @param {!QuickUnlockScreen} screen
+   * @return {!boolean}
+   */
+  isScreenActive: function(screen) {
+    var subpage = this.currentRoute.subpage;
+    return subpage.length > 0 && subpage[subpage.length - 1] == screen;
+  },
+
+  /**
+   * Navigate to the given screen.
+   * @param {!QuickUnlockScreen} screen
+   */
+  navigateToScreen: function(screen) {

[tommycli, 2016/06/24 00:56:39]

With only 3 callsites, I'm not sure it's worthwhile to abstract this method into
a behavior.

[jdufault, 2016/06/29 19:06:39]

Done.

+    this.currentRoute = {
+      page: 'basic',
+      section: 'people',
+      subpage: this.getSubpagesForScreen_(screen)
+    };
+  },
+
+  /**
+   * Returns the subpages to use in the router for the given screen.
+   * @param {!QuickUnlockScreen} screen
+   * @return {!Array<QuickUnlockScreen>}
+   * @private
+   */
+  getSubpagesForScreen_: function(screen) {

[tommycli, 2016/06/24 00:56:39]

I think we can eliminate this method, since each of these switch cases has only
one callsite.

[jdufault, 2016/06/29 19:06:39]

Done.

+    switch (screen) {
+      case QuickUnlockScreen.AUTHENTICATE:
+        return [QuickUnlockScreen.AUTHENTICATE];
+      case QuickUnlockScreen.CHOOSE_METHOD:
+        return [QuickUnlockScreen.CHOOSE_METHOD];
+      case QuickUnlockScreen.SETUP_PIN:
+        return [QuickUnlockScreen.CHOOSE_METHOD, QuickUnlockScreen.SETUP_PIN];
+    }
+  }
+};

[tommycli, 2016/06/24 00:56:39]

I don't think this behavior is "worth it". I don't think it decreases the SLOC
by much, if at all.

[jdufault, 2016/06/29 19:06:39]

I've removed everything except isScreenActive.