Do not perform online revocation checking when the user has explicitly disabled it, except for when…

net/base/x509_certificate.h

Index: net/base/x509_certificate.h
diff --git a/net/base/x509_certificate.h b/net/base/x509_certificate.h
index 4055f0a3db98695c46e872983b84a4e638437dc9..b75098c5edacb45d232f2d58fcff9481bc1a8bf5 100644
--- a/net/base/x509_certificate.h
+++ b/net/base/x509_certificate.h
@@ -89,9 +89,31 @@ class NET_EXPORT X509Certificate
   };
 
   enum VerifyFlags {
+    // If set, enables online revocation checking via CRLs and OCSP for the
+    // certificate chain.
     VERIFY_REV_CHECKING_ENABLED = 1 << 0,
+
+    // If set, and the certificate being verified may be an EV certificate,
+    // attempt to verify the certificate according to the EV processing
+    // guidelines. In order to successfully verify a certificate as EV,
+    // either an online or offline revocation check must be successfully
+    // completed. To ensure it's possible to complete a revocation check,
+    // callers should also specify either VERIFY_REV_CHECKING_ENABLED or
+    // VERIFY_REV_CHECKING_ENABLED_EV_ONLY (to enable online checks), and
+    // VERIFY_CERT_IO_ENABLED (to enable network fetches for online checks).
     VERIFY_EV_CERT = 1 << 1,
+
+    // If set, permits NSS to use the network when verifying certificates,
+    // such as to fetch missing intermediates or to check OCSP or CRLs.
+    // TODO(rsleevi): http://crbug.com/143300 - Define this flag for all
+    // verification engines with well-defined semantics, rather than being
+    // NSS only.
     VERIFY_CERT_IO_ENABLED = 1 << 2,
+
+    // If set, enables online revocation checking via CRLs or OCSP, but only
+    // for certificates which may be EV, and only when VERIFY_EV_CERT is also
+    // set.
+    VERIFY_REV_CHECKING_ENABLED_EV_ONLY = 1 << 3,

[wtc, 2012/08/17 00:34:44]

Nit: the fact that this flag is tacked on by CertVerifyProc::Verify()
internally probably should be described.  Perhaps
this flag should be considered as an internal flag?

[Ryan Sleevi, 2012/08/17 00:37:18]

The intent is to make it not an internal-only flag; http://crbug.com/142974

   };
 
   enum Format {