Add unittests for net::TestRootCerts and regenerate test certificates

net/data/ssl/certificates/README

 This directory contains various certificates for use with SSL-related
 unit tests.
 
 - google.binary.p7b
 - google.chain.pem
 - google.pem_cert.p7b
 - google.pem_pkcs7.p7b
 - google.pkcs7.p7b
 - google.single.der
 - google.single.pem
 - thawte.single.pem : Certificates for testing parsing of different formats.
 
 - googlenew.chain.pem : The refreshed Google certificate
      (valid until Sept 30 2013).
 
 - mit.davidben.der : An expired MIT client certificate.
 
 - foaf.me.chromium-test-cert.der : A client certificate for a FOAF.ME identity
      created for testing.
 
 - www_us_army_mil_cert.der
 - dod_ca_17_cert.der
 - dod_root_ca_2_cert.der : A certificate chain for regression tests of
      http://crbug.com/31497.
 
-- expired_cert.pem : An expired certificate, used by test_server.cc.
-
-- ok_cert.pem : A valid certificate, used by test_server.cc
-
-- root_ca_cert.crt : The testing root CA used to sign the test_server.cc's
-     certificates.
-
 - unosoft_hu_cert : Certificate used by X509CertificateTest.UnoSoftCertParsing.
 
 - client.p12 : A PKCS #12 file containing a client certificate and a private
      key created for testing.  The password is "12345".
 
 - client-nokey.p12 : A PKCS #12 file containing a client certificate (the same
      as the one in client.p12) but no private key. The password is "12345".
 
 - punycodetest.der : A test self-signed server certificate with punycode name.
      The common name is "xn--wgv71a119e.com" (日本語.com)
@@ skipping 162 matching lines @@
      2048-bit root. For clients that only support the GTE root, two versions
      of the Baltimore root were cross-signed by GTE, namely
      _cross_certified_[1,2].pem. _omniroot_chain.pem contains a certificate
      chain that was issued under the Baltimore root. Combined, these
      certificates can be used to test real-world cross-signing; in practice,
      they are used to test certain workarounds for OS X's chain building code.
 
 - no_subject_common_name_cert.pem: Used to test the function that generates a
   NSS certificate nickname for a user certificate. This certificate's Subject
   field doesn't have a common name.
+
+- expired_cert.pem
+- ok_cert.pem
+- root_ca_cert.pem
+     These certificates are the common certificates used by the Python test
+     server for simulating HTTPS connections. They are generated by running
+     the script net/data/ssl/scripts/generate-test-certs.sh.
+