Implement the encrypt-then-MAC TLS extension.

net/socket/ssl_client_socket_nss.cc

Index: net/socket/ssl_client_socket_nss.cc
===================================================================
--- net/socket/ssl_client_socket_nss.cc	(revision 252347)
+++ net/socket/ssl_client_socket_nss.cc	(working copy)
@@ -3211,6 +3211,12 @@
                          "SSL_ENABLE_SIGNED_CERT_TIMESTAMPS");
   }
 
+  rv = SSL_OptionSet(nss_fd_, SSL_ENABLE_ENCRYPT_THEN_MAC, PR_TRUE);
+  if (rv != SECSuccess) {
+    LogFailedNSSFunction(
+        net_log_, "SSL_OptionSet", "SSL_ENABLE_ENCRYPT_THEN_MAC");
+  }
+
   rv = SSL_OptionSet(nss_fd_, SSL_HANDSHAKE_AS_CLIENT, PR_TRUE);
   if (rv != SECSuccess) {
     LogFailedNSSFunction(net_log_, "SSL_OptionSet", "SSL_HANDSHAKE_AS_CLIENT");