Certificate Transparency: Require SCTs for EV certificates.

Add a flag to enforce the policy detailed here:
http://dev.chromium.org/Home/chromium-security/certificate-transparency

BUG=397458

Review URL: https://codereview.chromium.org/422063004

Cr-Commit-Position: refs/heads/master@{#306612}
diff --git a/net/socket/ssl_client_socket_openssl.h b/net/socket/ssl_client_socket_openssl.h
index 53d33c4c..6343cb7 100644
--- a/net/socket/ssl_client_socket_openssl.h
+++ b/net/socket/ssl_client_socket_openssl.h
@@ -304,6 +304,8 @@
 
   TransportSecurityState* transport_security_state_;
 
+  CertPolicyEnforcer* const policy_enforcer_;
+
   // pinning_failure_log contains a message produced by
   // TransportSecurityState::CheckPublicKeyPins in the event of a
   // pinning failure. It is a (somewhat) human-readable string.