Replace Manage Languages with dialog and dropdown item

chrome/browser/resources/settings/languages_page/add_languages_dialog.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 'settings-add-languages-dialog' is a dialog for enabling
+ * languages.
+ */
+Polymer({
+  is: 'settings-add-languages-dialog',
+
+  properties: {
+    /** @type {!LanguagesModel|undefined} */
+    languages: {
+      type: Object,
+      notify: true,
+    },
+
+    /** @type {!LanguageHelper} */
+    languageHelper: Object,
+
+    /** @private {!Set<string>} */
+    languagesToAdd_: {
+      type: Object,
+      value: function() { return new Set(); },
+    },
+
+    /** @private */
+    disableActionButton_: {
+      type: Boolean,
+      value: true,
+    },
+  },
+
+  attached: function() {
+    this.$.dialog.showModal();
+  },
+
+  /**
+   * Returns the supported languages that are not yet enabled.

[stevenjb, 2016/08/23 17:08:04]

The dependencies for this are subtle, we should document that
languageHelper.isLanguageEnabled depends on languages.enabled.* (assuming that
is the case).

[michaelpg, 2016/08/23 23:37:06]

Done.

+   * @param {!Array<!chrome.languageSettingsPrivate.Language>}
+   *     supportedLanguages
+   * @return {!Array<!chrome.languageSettingsPrivate.Language>}
+   * @private
+   */
+  getAvailableLanguages_: function(supportedLanguages) {
+    return supportedLanguages.filter(function(language) {
+      return !this.languageHelper.isLanguageEnabled(language.code);
+    }.bind(this));
+  },
+
+  /**
+   * True if the user has chosen to add this language (checked its checkbox).
+   * @return {boolean}
+   * @private
+   */
+  willAdd_: function(languageCode) {
+    return this.languagesToAdd_.has(languageCode);
+  },
+
+  /**
+   * Handler for checking or unchecking a language item.
+   * @param {!{model: !{item: !chrome.languageSettingsPrivate.Language},
+   *           target: !PaperCheckboxElement}} e
+   * @private
+   */
+  onLanguageCheckboxChange_: function(e) {
+    // Add or remove the item to the Set. No need to worry about data binding:
+    // willAdd_ is called to initialize the checkbox state (in case the
+    // iron-list re-uses a previous checkbox), and the checkbox can only be
+    // changed after that by user action.
+    var code = e.model.item.code;
+    if (e.target.checked)
+      this.languagesToAdd_.add(code);
+    else
+      this.languagesToAdd_.delete(code);
+
+    this.disableActionButton_ = !this.languagesToAdd_.size;
+  },
+
+  /** @private */
+  onCancelButtonTap_: function() {
+    this.$.dialog.close();
+  },
+
+  /**
+   * Enables the checked languages.
+   * @private
+   */
+  onActionButtonTap_: function() {
+    this.$.dialog.close();
+    for (var languageCode of this.languagesToAdd_)
+      this.languageHelper.enableLanguage(languageCode);
+  },
+});