MD Extensions: Show messages for no extensions, and for no search results

chrome/browser/resources/md_extensions/manager.js

 // Copyright 2015 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.
 
 cr.define('extensions', function() {
   'use strict';
 
   /**
    * Compares two extensions to determine which should come first in the list.
    * @param {chrome.developerPrivate.ExtensionInfo} a
@@ skipping 80 matching lines @@
         },
       },
 
       /** @type {!Array<!chrome.developerPrivate.ExtensionInfo>} */
       apps: {
         type: Array,
         value: function() {
           return [];
         },
       },
+
+      /**
+       * Prevents page content from showing before data is first loaded.
+       * @private
+       */
+      didInitPage_: {
+        type: Boolean,
+        value: false,
+      },
     },
 
     listeners: {
       'items-list.extension-item-show-details': 'onShouldShowItemDetails_',
       'items-list.extension-item-show-errors': 'onShouldShowItemErrors_',
     },
 
     created: function() {
       this.readyPromiseResolver = new PromiseResolver();
     },
@@ skipping 53 matching lines @@
      */
     showItemDetails: function(data) {
       this.changePage({page: Page.DETAILS, extensionId: data.id});
     },
 
     /**
      * Initializes the page to reflect what's specified in the url so that if
      * the user visits chrome://extensions/?id=..., we land on the proper page.
      */
     initPage: function() {
+      this.didInitPage_ = true;
       this.changePage(this.navigationHelper_.getCurrentPage(), true);
     },
 
     /**
      * @param {!CustomEvent} event
      * @private
      */
     onFilterChanged_: function(event) {
       this.filter = /** @type {string} */ (event.detail);
     },
@@ skipping 45 matching lines @@
     /**
      * @return {?chrome.developerPrivate.ExtensionInfo}
      * @private
      */
     getData_: function(id) {
       return this.extensions[this.getIndexInList_('extensions', id)] ||
           this.apps[this.getIndexInList_('apps', id)];
     },
 
     /**
-     * @return {boolean} Whether the list should be visible.
-     * @private
-     */
-    computeListHidden_: function() {
-      return this.$['items-list'].items.length == 0;
-    },
-
-    /**
      * Creates and adds a new extensions-item element to the list, inserting it
      * into its sorted position in the relevant section.
      * @param {!chrome.developerPrivate.ExtensionInfo} item The extension
      *     the new element is representing.
      */
     addItem: function(item) {
       var listId = this.getListId_(item.type);
       // We should never try and add an existing item.
       assert(this.getIndexInList_(listId, item.id) == -1);
       var insertBeforeChild = this[listId].findIndex(function(listEl) {
@@ skipping 189 matching lines @@
     }
 
     /** @override */
     showKeyboardShortcuts() {
       this.manager_.changePage({page: Page.SHORTCUTS});
     }
   }
 
   return {Manager: Manager};
 });