webRequest.onAuthRequired listeners can provide authentication credentials.

net/base/auth.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.
 
 #ifndef NET_BASE_AUTH_H__
 #define NET_BASE_AUTH_H__
 #pragma once
 
 #include <string>
 
@@ skipping 47 matching lines @@
   string16 password;  // the password supplied to us for auth.
 
   // We wouldn't instantiate this class if we didn't need authentication.
   AuthData();
 
  private:
   friend class base::RefCountedThreadSafe<AuthData>;
   ~AuthData();
 };
 
+class AuthCredentials {
+ public:
+  AuthCredentials();
+  ~AuthCredentials();
+
+  bool is_valid;
+  string16 username;
+  string16 password;
+};
+
 }  // namespace net
 
 #endif  // NET_BASE_AUTH_H__