[Extensions] Update extensions UI to observe events and add test

third_party/closure_compiler/externs/developer_private.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.
 
 /** @fileoverview Externs generated from namespace: developerPrivate */
 
 /**
  * @const
  */
 chrome.developerPrivate = {};
@@ skipping 343 matching lines @@
 /**
  * @typedef {{
  *   name: string
  * }}
  */
 var ProjectInfo;
 
 /**
  * @typedef {{
  *   event_type: !chrome.developerPrivate.EventType,
- *   item_id: string
+ *   item_id: string,
+ *   extensionInfo: (ExtensionInfo|undefined)
  * }}
  */
 var EventData;
 
 /**
  * @typedef {{
  *   extensionId: string,
  *   pathSuffix: string,
  *   message: string,
  *   manifestKey: (string|undefined),
@@ skipping 181 matching lines @@
 
 /**
  * @param {InspectOptions} options
  * @param {function():void=} callback
  * @deprecated Use openDevTools
  */
 chrome.developerPrivate.inspect = function(options, callback) {};
 
 /** @type {!ChromeEvent} */
 chrome.developerPrivate.onItemStateChanged;