Add a script to update the expected errors for

net/data/verify_certificate_chain_unittest/generate-incorrect-trust-anchor.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, but the trust anchor used is
 incorrect (neither subject nor signature matches). Verification is expected to
 fail."""
 
 import common
 
 # Self-signed root certificate, which is NOT saved as the trust anchor.
 root = common.create_self_signed_root_certificate('Root')
 
 # Intermediate certificate.
 intermediate = common.create_intermediate_certificate('Intermediate', root)
 
 # Target certificate.
 target = common.create_end_entity_certificate('Target', intermediate)
 
 # Self-signed root certificate, not part of chain, which is saved as trust
 # anchor.
 bogus_root = common.create_self_signed_root_certificate('BogusRoot')
 
 chain = [target, intermediate]
 trusted = common.TrustAnchor(bogus_root, constrained=False)
 time = common.DEFAULT_TIME
 verify_result = False
-errors = ['Signature verification failed', 'VerifySignedData failed']
+errors = """Signature verification failed
+VerifySignedData failed"""
 
 common.write_test_file(__doc__, chain, trusted, time, verify_result, errors)