md-settings: Added settings for fingerprint unlock.

chrome/browser/resources/settings/people_page/fingerprint_list.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.
+
+/**
+ * @fileoverview
+ * Polymer element for displaying a list of fingerprints.
+ *
+ * Example:
+ *    <settings-fingerprint-list></settings-fingerprint-list>
+ */
+
+(function() {
+'use strict';
+
+/**
+ * The max number of fingerprints this list can hold.
+ * @type {number}
+ * @const
+ */
+var MAX_NUMBER_FINGERPRINTS_ALLOWED = 5;
+
+Polymer({
+  is: 'settings-fingerprint-list',
+
+  behaviors: [
+    I18nBehavior,
+  ],
+
+  properties: {
+    /**
+     * The list of fingerprint objects.
+     * @type {Array<Object>}
+     * @private

[stevenjb, 2016/12/07 23:25:40]

Combine lines:
@private {Array<Object>}

[sammiequon, 2016/12/08 03:50:50]

Done.

+     */
+    fingerprints_: {
+      type: Array,
+      value: function() {
+        return [];
+      },
+      notify: true,
+    }
+  },
+
+  /**
+   * Returns the text to be displayed when the user has set up
+   * |MAX_NUMBER_FINGERPRINTS_ALLOWED|.
+   * @return {string}
+   * @private
+   */
+  getFingerprintButtonCannotAddText_: function() {
+    return this.i18n('lockScreenCannotAddFingerprint',
+                     MAX_NUMBER_FINGERPRINTS_ALLOWED);
+  },
+
+  /**
+   * Check if the registered fingerprints has a fingerprint with name |name|.

[stevenjb, 2016/12/07 23:25:40]

s/the registered fingerprints/|fingerprints_|/ (or 'the list of registered
fingerprints')

[sammiequon, 2016/12/08 03:50:50]

Done.

+   * @param {string} name The name we are looking for.
+   * @return {boolean}
+   * @private
+   */
+  isNameUsed_: function(name) {
+    return !!this.fingerprints_.find(function(e) {
+      return e.name == name;
+    });
+  },
+
+  /**
+   * Adds a fingerprint with a default name.
+   * @private
+   */
+  onAddFingerprint_: function() {
+    // Determines what the newly added fingerprint's name should be.
+    // TODO(sammiequon): Add fingerprint using private API once it is ready.

[stevenjb, 2016/12/07 23:25:40]

Rather than committing fake code in the initial UI, consider implementing a fake
interface that can later be replaced with the real interface once implemented.
That will require less fake code here, and will assist in testing the UI later
(i.e. we can use the fake interface implementation in tests).

[sammiequon, 2016/12/08 03:50:50]

I do not think too much of the initial code here will be deleted at the end.
Once the api is ready we just have signal it to enroll/delete a fingerprint. The
stuff in this CL should hopefully be only altered minimally.

[stevenjb, 2016/12/08 16:49:40]

Shouldn't this whole function just be:

chrome.fingerprintPrivate.addFingerprint()?

Determining the name is something I would expect the model to do, not the UI. I
would really much prefer to see this fake implementation in a fake api, i.e.
fakeFingerprintPrivate.

Same with onFingerprintDelete.

[sammiequon, 2016/12/08 20:22:40]

I put the naming stuff here since the users change names here via paper-input so
i thought it'll be nice to keep them in the same place. I'm not strongly against
moving this all out into the fakeFingerprintPrivate (next CL) though. What do
you think?

+
+    var fingerprintName;
+    for (var i = 1; i <= MAX_NUMBER_FINGERPRINTS_ALLOWED; ++i) {
+      fingerprintName = this.i18n('lockScreenFingerprintNewName', i);
+      if (this.isNameUsed_(fingerprintName))
+        continue;
+      break;
+    }
+    this.push('fingerprints_', { 'name': fingerprintName });
+  },
+
+  /**
+   * Deletes a fingerprint from |fingerprints_|.
+   * @private
+   */
+  onFingerprintDelete_: function(e) {
+    // TODO(sammiequon): Remove fingerprint using private API once it is ready.
+    this.splice('fingerprints_', e.model.index, 1);
+  },
+
+  /**
+   * Checks whether another fingerprint can be added.
+   * @return {boolean}
+   * @private
+   */
+  canAddNewFingerprint_: function(length) {
+    return length < MAX_NUMBER_FINGERPRINTS_ALLOWED;
+  }
+});
+})();