webRequest.onAuthRequired listeners can provide authentication credentials.

net/base/net_log_event_type_list.h

 // Copyright (c) 2011 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.
 
 // NOTE: No header guards are used, since this file is intended to be expanded
 // directly into net_log.h. DO NOT include this file anywhere else.
 
 // In the event of a failure, a many end events will have a |net_error|
 // parameter with the integer error code associated with the failure.  Most
 // of these parameters are not individually documented.
@@ skipping 1189 matching lines @@
 EVENT_TYPE(CHROME_EXTENSION_MODIFIED_HEADERS)
 
 // This event is created when a Chrome extension tried to modify a request
 // but was ignored due to a conflict.
 //
 //  {
 //    "extension_id": <Extension ID that was ignored>
 //  }
 EVENT_TYPE(CHROME_EXTENSION_IGNORED_DUE_TO_CONFLICT)
 
+// This event is created when a Chrome extension provides authentication
+// credentials.
+//
+//  {
+//    "extension_id": <Extension ID that provides credentials>
+//  }
+EVENT_TYPE(CHROME_EXTENSION_PROVIDE_AUTH_CREDENTIALS)
+
 // ------------------------------------------------------------------------
 // HostBlacklistManager
 // ------------------------------------------------------------------------
 
 // TODO(joaodasilva): Layering violation, see comment above.
 // http://crbug.com/90674.
 
 // This event is created when a request is blocked by a policy.
 EVENT_TYPE(CHROME_POLICY_ABORTED_REQUEST)