[Apps Developer Tool] Show installation warnings as chrome://extensions.

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 {
 
   enum ItemType {
     hosted_app,
     packaged_app,
     legacy_packaged_app,
     extension,
     theme
   };
 
   dictionary ItemInspectView {
     // path to the inspect page.
     DOMString path;
 
     // For lazy background pages, the value is -1.
     long render_process_id;
 
     long render_view_id;
     boolean incognito;
   };
 
+  dictionary InstallWarning {
+    boolean is_html;
+    DOMString message;
+  };
+
   dictionary ItemInfo {
     DOMString id;
     DOMString name;
     DOMString version;
     DOMString description;
     boolean may_disable;
     boolean enabled;
     DOMString? disabled_reason;
     boolean isApp;
     ItemType type;
     boolean allow_activity;
     boolean allow_file_access;
     boolean wants_file_access;
     boolean incognito_enabled;
     boolean is_unpacked;
     boolean allow_reload;
     boolean terminated;
     boolean allow_incognito;
     DOMString icon_url;
 
     // Path of an unpacked extension.
     DOMString? path;
 
     // Options settings page for the item.
     DOMString? options_url;
     DOMString? app_launch_url;
     DOMString? homepage_url;
     DOMString? update_url;
+    InstallWarning[] install_warnings;
     boolean offline_enabled;
 
     // All views of the current extension.
     ItemInspectView[] views;
   };
 
   dictionary InspectOptions {
     DOMString extension_id;
     DOMString render_process_id;
     DOMString render_view_id;
@@ skipping 135 matching lines @@
     // translated string to use in the apps_debugger app UI.
     static void getStrings(GetStringsCallback callback);
   };
 
   interface Events {
     // Fired when a item state is changed.
     static void onItemStateChanged(EventData response);
   };
 
 };