[Extensions Page] Add a listener on extension list for "hasExtensions" changing

chrome/browser/resources/extensions/extension_list.js

 // Copyright (c) 2012 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.
 
 <include src="extension_error.js">
 
 ///////////////////////////////////////////////////////////////////////////////
 // ExtensionFocusRow:
 
 /**
@@ skipping 217 matching lines @@
      */
     enableAppInfoDialog_: false,
 
     /**
      * Initializes the list.
      */
     initialize: function() {
       /** @private {!Array<ExtensionInfo>} */
       this.extensions_ = [];
 
+      /** @type {?function()} */
+      this.onExtensionCountChanged = null;

[Dan Beam, 2015/04/27 16:17:05]

why does this need to ever be assigned/created dynamically?

[Devlin, 2015/04/27 18:28:30]

Per offline conversation, extracted this into a delegate.

+
       /**
        * |loadFinished| should be used for testing purposes and will be
        * fulfilled when this list has finished loading the first time.
        * @type {Promise}
        * */
       this.loadFinished = new Promise(function(resolve, reject) {
         /** @private {function(?)} */
         this.resolveLoadFinished_ = resolve;
       }.bind(this));
 
       chrome.developerPrivate.onItemStateChanged.addListener(
           function(eventData) {
         var EventType = chrome.developerPrivate.EventType;
         switch (eventData.event_type) {
           case EventType.VIEW_REGISTERED:
           case EventType.VIEW_UNREGISTERED:
           case EventType.INSTALLED:
           case EventType.LOADED:
           case EventType.UNLOADED:
           case EventType.ERROR_ADDED:
           case EventType.PREFS_CHANGED:
             if (eventData.extensionInfo)
               this.updateExtension_(eventData.extensionInfo);
             break;
           case EventType.UNINSTALLED:
+            var index = this.getIndexOfExtension_(eventData.item_id);
+            this.extensions_.splice(index, 1);
             var childNode = $(eventData.item_id);
             childNode.parentNode.removeChild(childNode);
             break;
           default:
             assertNotReached();
         }
+
+        if ((eventData.event_type == EventType.INSTALLED ||
+             eventData.event_type == EventType.UNINSTALLED) &&
+            this.onExtensionCountChanged) {
+          this.onExtensionCountChanged();
+        }
       }.bind(this));
     },
 
     /**
      * Updates the extensions on the page.
      * @param {boolean} incognitoAvailable Whether or not incognito is allowed.
      * @param {boolean} enableAppInfoDialog Whether or not the app info dialog
      *     is enabled.
      * @return {Promise} A promise that is resolved once the extensions data is
      *     fully updated.
@@ skipping 48 matching lines @@
       var idToOpenOptions = this.getOptionsQueryParam_();
       if (idToOpenOptions && $(idToOpenOptions))
         this.showEmbeddedExtensionOptions_(idToOpenOptions, true);
     },
 
     /** @return {number} The number of extensions being displayed. */
     getNumExtensions: function() {
       return this.extensions_.length;
     },
 
+    /**
+     * @param {string} id The id of the extension.
+     * @return {number} The index of the extension with the given id.
+     * @private
+     */
+    getIndexOfExtension_: function(id) {
+      for (var i = 0; i < this.extensions_.length; ++i) {
+        if (this.extensions_[i].id == id)
+          return i;
+      }
+      return -1;
+    },
+
     getIdQueryParam_: function() {
       return parseQueryParams(document.location)['id'];
     },
 
     getOptionsQueryParam_: function() {
       return parseQueryParams(document.location)['options'];
     },
 
     /**
      * Creates or updates all extension items from scratch.
@@ skipping 709 matching lines @@
       overlay.setInitialFocus();
     },
 
     /**
      * Updates the node for the extension.
      * @param {!ExtensionInfo} extension The information about the extension to
      *     update.
      * @private
      */
     updateExtension_: function(extension) {
-      var currIndex = -1;
-      for (var i = 0; i < this.extensions_.length; ++i) {
-        if (this.extensions_[i].id == extension.id) {
-          currIndex = i;
-          break;
-        }
-      }
+      var currIndex = this.getIndexOfExtension_(extension.id);
       if (currIndex != -1) {
         // If there is a current version of the extension, update it with the
         // new version.
         this.extensions_[currIndex] = extension;
       } else {
         // If the extension isn't found, push it back and sort. Technically, we
         // could optimize by inserting it at the right location, but since this
         // only happens on extension install, it's not worth it.
         this.extensions_.push(extension);
         this.extensions_.sort(compareExtensions);
       }
 
       var node = /** @type {ExtensionFocusRow} */ ($(extension.id));
       if (node) {
         this.updateNode_(extension, node);
       } else {
         var nextExt = this.extensions_[this.extensions_.indexOf(extension) + 1];
         this.createNode_(extension, nextExt ? $(nextExt.id) : null);
       }
     }
   };
 
   return {
     ExtensionList: ExtensionList
   };
 });