webRequest.onAuthRequired listeners can provide authentication credentials.

net/base/auth.h

Index: net/base/auth.h
diff --git a/net/base/auth.h b/net/base/auth.h
index 51f8db95388cd699b10e90a4effd6f76f321e0e9..6dcd913a739947e065aa07c76c03e9f1b0b22cb0 100644
--- a/net/base/auth.h
+++ b/net/base/auth.h
@@ -65,6 +65,31 @@ class AuthData : public base::RefCountedThreadSafe<AuthData> {
   ~AuthData();
 };
 
+// Authentication Credentials for an authentication credentials.
+class NET_EXPORT AuthCredentials {
+ public:
+  AuthCredentials();
+  ~AuthCredentials();
+
+  // |is_valid| is true if the username and password have been set. Since
+  // username and/or password may be empty, this is needed to differentiate
+  // that case.
+  bool is_valid;
+
+  // The username to provide, possibly empty. This should be ASCII only to
+  // minimize compatibility problems, but arbitrary UTF-16 strings are allowed
+  // and will be attempted.
+  string16 username;
+
+  // The password to provide, possibly empty. This should be ASCII only to
+  // minimize compatibility problems, but arbitrary UTF-16 strings are allowed
+  // and will be attempted.
+  string16 password;
+
+  // Intentionally allowing the implicit copy constructor and assignment
+  // operators.
+};
+
 }  // namespace net
 
 #endif  // NET_BASE_AUTH_H__