Update SSL error handling code to account for Subject CN deprecation

components/ssl_errors/error_classification.h

Index: components/ssl_errors/error_classification.h
diff --git a/components/ssl_errors/error_classification.h b/components/ssl_errors/error_classification.h
index b8c472df6697f0607b8cd6b37185ed63fd3c3d9a..01f0460988ecd9934b32b131930bc039f406f432 100644
--- a/components/ssl_errors/error_classification.h
+++ b/components/ssl_errors/error_classification.h
@@ -28,6 +28,34 @@ typedef std::vector<std::string> HostnameTokens;
 
 // Methods for identifying specific error causes. ------------------------------
 
+// Events for UMA. Do not reorder or change!
+enum SSLInterstitialCause {
+  CLOCK_PAST,
+  CLOCK_FUTURE,
+  WWW_SUBDOMAIN_MATCH,         // Deprecated
+  SUBDOMAIN_MATCH,             // Deprecated
+  SUBDOMAIN_INVERSE_MATCH,     // Deprecated
+  SUBDOMAIN_OUTSIDE_WILDCARD,  // Deprecated
+  HOST_NAME_NOT_KNOWN_TLD,
+  LIKELY_MULTI_TENANT_HOSTING,  // Deprecated
+  LOCALHOST,
+  PRIVATE_URL,
+  AUTHORITY_ERROR_CAPTIVE_PORTAL,  // Deprecated in M47.
+  SELF_SIGNED,
+  EXPIRED_RECENTLY,
+  LIKELY_SAME_DOMAIN,  // Deprecated
+  // In Chrome 58, SubjectCN matching was deprecated, deprecating original
+  // metrics to be replaced with the 2-suffixed variants below.
+  NO_SUBJECT_ALT_NAMES,
+  WWW_SUBDOMAIN_MATCH2,
+  SUBDOMAIN_MATCH2,
+  SUBDOMAIN_INVERSE_MATCH2,
+  SUBDOMAIN_OUTSIDE_WILDCARD2,
+  LIKELY_MULTI_TENANT_HOSTING2,
+  LIKELY_SAME_DOMAIN2,
+  UNUSED_INTERSTITIAL_CAUSE_ENTRY,
+};
+
 // What is known about the accuracy of system clock.  Do not change or
 // reorder; these values are used in an UMA histogram.
 enum ClockState {
@@ -110,14 +138,9 @@ bool IsCertLikelyFromMultiTenantHosting(const GURL& request_url,
 bool IsCertLikelyFromSameDomain(const GURL& request_url,
                                 const net::X509Certificate& cert);
 
-// Returns true if the site's hostname differs from one of the DNS
-// names in the certificate (CN or SANs) only by the presence or
-// absence of the single-label prefix "www". E.g.: (The first domain
-// is hostname and the second domain is a DNS name in the certificate)
-//     www.example.com ~ example.com -> true
-//     example.com ~ www.example.com -> true
-//     www.food.example.com ~ example.com -> false
-//     mail.example.com ~ example.com -> false
+// Returns true if the site's hostname differs from one of the DNS names in
+// |dns_names| only by the presence or absence of the single-label prefix "www".
+// The matching name from the certificate is returned in |www_match_host_name|.
 bool GetWWWSubDomainMatch(const GURL& request_url,
                           const std::vector<std::string>& dns_names,
                           std::string* www_match_host_name);