Rewrite DownloadsApiTest in C++.

chrome/common/chrome_notification_types.h

 // 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.
 
 #ifndef CHROME_COMMON_CHROME_NOTIFICATION_TYPES_H_
 #define CHROME_COMMON_CHROME_NOTIFICATION_TYPES_H_
 #pragma once
 
 #include "content/public/browser/notification_types.h"
 
@@ skipping 559 matching lines @@
   // sender is a std::string representing the extension id, and the details
   // are a std::string with some message. This is particularly useful when you
   // want to have C++ code wait for javascript code to do something.
   NOTIFICATION_EXTENSION_TEST_MESSAGE,
 
   // Sent when an bookmarks extensions API function was successfully invoked.
   // The source is the id of the extension that invoked the function, and the
   // details are a pointer to the const BookmarksFunction in question.
   NOTIFICATION_EXTENSION_BOOKMARKS_API_INVOKED,
 
+  // Sent when a downloads extensions API event is fired. The source is an
+  // ExtensionDownloadsEventRouter::NotificationSource, and the details is a
+  // std::string containing json. Used for testing.
+  NOTIFICATION_EXTENSION_DOWNLOADS_EVENT,
+
   // Sent when an omnibox extension has sent back omnibox suggestions. The
   // source is the profile, and the details are an ExtensionOmniboxSuggestions
   // object.
   NOTIFICATION_EXTENSION_OMNIBOX_SUGGESTIONS_READY,
 
   // Sent when the user accepts the input in an extension omnibox keyword
   // session. The source is the profile.
   NOTIFICATION_EXTENSION_OMNIBOX_INPUT_ENTERED,
 
   // Sent when an omnibox extension has updated the default suggestion. The
@@ skipping 579 matching lines @@
   // Currently only Content and Chrome define and use notifications.
   // Custom notifications not belonging to Content and Chrome should start
   // from here.
   NOTIFICATION_CHROME_END,
 };
 
 }  // namespace chrome
 
 
 #endif  // CHROME_COMMON_CHROME_NOTIFICATION_TYPES_H_