Refactor how net/data/verify_certificate_chain_unittest/*

net/data/verify_certificate_chain_unittest/constrained-root-basic-constraints-ca-false/generate-chains.py

 #!/usr/bin/python
 # Copyright (c) 2015 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.
 
 """Certificate chain with 1 intermediate and a trust anchor. The trust anchor
 has a basic constraints extension that indicates it is NOT a CA. Verification
 is expected to succeed even though the trust anchor enforces constraints, since
 the CA part of basic constraints is not enforced."""
 
+import sys
+sys.path += ['..']
+
 import common
 
 # Self-signed root certificate (used as trust anchor) with non-CA basic
 # constraints.
 root = common.create_self_signed_root_certificate('Root')
 root.get_extensions().set_property('basicConstraints', 'critical,CA:false')
 
 # Intermediate certificate.
 intermediate = common.create_intermediate_certificate('Intermediate', root)
 
 # Target certificate.
 target = common.create_end_entity_certificate('Target', intermediate)
 
-chain = [target, intermediate]
-trusted = common.TrustAnchor(root, constrained=True)
-time = common.DEFAULT_TIME
-key_purpose = common.DEFAULT_KEY_PURPOSE
-verify_result = True
-errors = None
-
-common.write_test_file(__doc__, chain, trusted, time, key_purpose,
-                       verify_result, errors)
+chain = [target, intermediate, root]
+common.write_chain(__doc__, chain, 'chain.pem')