bluetooth: Add service list to DeviceDetailsPage in internals page.

chrome/browser/resources/bluetooth_internals/expandable_list.js

+// Copyright 2017 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.
+
+/**
+ * Javascript for ExpandableList and ExpandableListItem, served from
+ *     chrome://bluetooth-internals/.
+ */
+
+cr.define('expandable_list', function() {
+  /** @const */ var List = cr.ui.List;
+  /** @const */ var ListItem = cr.ui.ListItem;
+
+  /**
+   * A list item that has expandable content that toggles when the item is
+   * clicked.
+   * @constructor
+   */
+  var ExpandableListItem = cr.ui.define('li');
+
+  ExpandableListItem.prototype = {
+    __proto__: ListItem.prototype,
+
+    /**
+     * Decorates the element as an expandable list item and caches the created
+     * content holders for implementations.
+     * @override
+     */
+    decorate: function() {
+      this.classList.add('expandable-list-item');
+      this.briefContent_ = document.createElement('div');
+      this.briefContent_.classList.add('brief-content');
+      this.briefContent_.addEventListener(
+          'click', this.toggleExpand_.bind(this));
+      this.appendChild(this.briefContent_);
+
+      this.expandedContent_ = document.createElement('div');
+      this.expandedContent_.classList.add('expanded-content');
+      this.appendChild(this.expandedContent_);
+    },
+
+    /**
+     * Toggles the expanded class on the item.
+     * @private
+     */
+    toggleExpand_: function() {
+      this.classList.toggle('expanded');
+    },
+  };
+
+  /**
+   * A list that contains expandable list items.
+   * @abstract
+   * @constructor
+   */
+  var ExpandableList = cr.ui.define('list');
+
+  ExpandableList.prototype = {
+    __proto__: List.prototype,
+
+    /**
+     * Decorates element as an expandable list and caches references to layout
+     * elements.
+     * @override
+     */
+    decorate: function() {
+      List.prototype.decorate.call(this);
+      this.classList.add('expandable-list');
+
+      this.emptyMessage_ = document.createElement('h3');
+      this.emptyMessage_.classList.add('empty-message');
+      this.emptyMessage_.hidden = true;
+      this.insertBefore(this.emptyMessage_, this.firstChild);
+
+      this.spinner_ = document.createElement('div');
+      this.spinner_.classList.add('spinner');
+      this.insertBefore(this.spinner_, this.firstChild);
+
+      this.autoExpands = true;
+      this.boundUpdateMessage_ = this.updateMessageDisplay_.bind(this);
+
+    },
+
+    /**
+     * Sets the data model of the list.
+     * @param {cr.ui.ArrayDataModel} data
+     */
+    setData: function(data) {
+      if (this.dataModel)
+        this.dataModel.removeEventListener('splice', this.boundUpdateMessage_);
+
+      this.dataModel = data;
+      this.dataModel.addEventListener('splice', this.boundUpdateMessage_);
+      this.updateMessageDisplay_();
+    },
+
+    /**
+     * Sets the empty message text.
+     * @param {string} message
+     */
+    setEmptyMessage: function(message) {
+      this.emptyMessage_.textContent = message;
+    },
+
+    /**
+     * Sets the loading state of the list. If |loading| is true, the loading
+     * spinner is dispayed.
+     * @param {boolean} loading
+     */
+    setLoading: function(loading) {
+      this.spinner_.hidden = !loading;

[dpapad, 2017/01/14 00:32:57]

FWIW, a hidden spinner still takes up precious CPU, doesn't it?

[mbrunson, 2017/01/14 01:36:12]

Does it? That seems to defeat the purpose of hidden/display:none if images still
take CPU cycles when they're not displayed...

+    },
+
+    /**
+     * Updates the display state of the empty message. If there are no items in
+     * the data model, the empty message is displayed.
+     */
+    updateMessageDisplay_: function() {
+      this.emptyMessage_.hidden = this.dataModel.length > 0;
+    },
+  };
+
+  return {
+    ExpandableListItem: ExpandableListItem,
+    ExpandableList: ExpandableList,
+  }
+});