Add a histogram for measuring the number of times we fall back to common name matching, when a cert…

net/cert/cert_verify_result.h

Index: net/cert/cert_verify_result.h
diff --git a/net/cert/cert_verify_result.h b/net/cert/cert_verify_result.h
index a00c03e4a242ad382be5161bec422f95fa62b03d..09deffa0998832975835fcbe8f28a0e403786042 100644
--- a/net/cert/cert_verify_result.h
+++ b/net/cert/cert_verify_result.h
@@ -62,6 +62,10 @@ class NET_EXPORT CertVerifyResult {
   // is_issued_by_additional_trust_anchor is true if the root CA used for this
   // verification came from the list of additional trust anchors.
   bool is_issued_by_additional_trust_anchor;
+
+  // True if a fallback to the common name was used when matching the host
+  // name, rather than using the subjectAltName.
+  bool common_name_fallback_used;
 };
 
 }  // namespace net