Add a DevTools warning for a missing subjectAltName

components/security_state/content/content_utils.cc

Index: components/security_state/content/content_utils.cc
diff --git a/components/security_state/content/content_utils.cc b/components/security_state/content/content_utils.cc
index ae007c335a78b8fc897250b621a3f22da0937e43..8fd95ea24825c849373a4394ec518338b0a8535d 100644
--- a/components/security_state/content/content_utils.cc
+++ b/components/security_state/content/content_utils.cc
@@ -226,6 +226,14 @@ blink::WebSecurityStyle GetSecurityStyle(
             !!security_info.certificate));
   }
 
+  if (security_info.cert_missing_subject_alt_name) {
+    security_style_explanations->broken_explanations.push_back(
+        content::SecurityStyleExplanation(
+            l10n_util::GetStringUTF8(IDS_SUBJECT_ALT_NAME_MISSING),
+            l10n_util::GetStringUTF8(IDS_SUBJECT_ALT_NAME_MISSING_DESCRIPTION),
+            !!security_info.certificate));
+  }
+
   // Record the presence of mixed content (HTTP subresources on an HTTPS
   // page).
   security_style_explanations->ran_mixed_content =