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

chrome/common/extensions/api/developer_private.idl

 // 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.
 
 // developerPrivate API.
 // This is a private API exposing developing and debugging functionalities for
 // apps and extensions.
 namespace developerPrivate {
 
   // DEPRECATED: Prefer ExtensionType.
@@ skipping 278 matching lines @@
     PackStatus status;
   };
 
   dictionary ProjectInfo {
     DOMString name;
   };
 
   dictionary EventData {
     EventType event_type;
     DOMString item_id;
+    ExtensionInfo? extensionInfo;
   };
 
   dictionary RequestFileSourceProperties {
     // The ID of the extension owning the file.
     DOMString extensionId;
 
     // The path of the file, relative to the extension; e.g., manifest.json,
     // script.js, or main.html.
     DOMString pathSuffix;
 
@@ skipping 182 matching lines @@
         static void inspect(InspectOptions options,
                             optional VoidCallback callback);
   };
 
   interface Events {
     // Fired when a item state is changed.
     static void onItemStateChanged(EventData response);
   };
 
 };