Remove support for dummy post-quantum padding.

Results written up at https://www.imperialviolet.org/2018/04/11/pqconftls.html

Change-Id: Ic8a916104706af54314e8a426a44087804975358
Reviewed-on: https://chromium-review.googlesource.com/1128160
Commit-Queue: Adam Langley <agl@chromium.org>
Reviewed-by: Ilya Sherman <isherman@chromium.org>
Reviewed-by: David Benjamin <davidben@chromium.org>
Cr-Commit-Position: refs/heads/master@{#583169}

net/socket/ssl_client_socket_impl.cc

@@ -77,9 +77,6 @@ const int kSSLClientSocketNoPendingResult = 1;
 // Default size of the internal BoringSSL buffers.
 const int kDefaultOpenSSLBufferSize = 17 * 1024;
 
-const base::Feature kPostQuantumPadding{"PostQuantumPadding",
-                                        base::FEATURE_DISABLED_BY_DEFAULT};
-
 std::unique_ptr<base::Value> NetLogPrivateKeyOperationCallback(
     uint16_t algorithm,
     NetLogCaptureMode mode) {
@@ -663,7 +660,6 @@ bool SSLClientSocketImpl::GetSSLInfo(SSLInfo* ssl_info) {
       SSL_is_token_binding_negotiated(ssl_.get());
   ssl_info->token_binding_key_param = static_cast<net::TokenBindingParam>(
       SSL_get_negotiated_token_binding_param(ssl_.get()));
-  ssl_info->dummy_pq_padding_received = SSL_dummy_pq_padding_used(ssl_.get());
   ssl_info->pinning_failure_log = pinning_failure_log_;
   ssl_info->ocsp_result = server_cert_verify_result_.ocsp_result;
   ssl_info->is_fatal_cert_error = is_fatal_cert_error_;
@@ -921,12 +917,6 @@ int SSLClientSocketImpl::Init() {
       break;
   }
 
-  const int dummy_pq_padding_len = base::GetFieldTrialParamByFeatureAsInt(
-      kPostQuantumPadding, "length", 0 /* default value */);
-  if (dummy_pq_padding_len > 0 && dummy_pq_padding_len < 15000) {
-    SSL_set_dummy_pq_padding_size(ssl_.get(), dummy_pq_padding_len);
-  }
-
   // OpenSSL defaults some options to on, others to off. To avoid ambiguity,
   // set everything we care about to an absolute value.
   SslSetClearMask options;

net/socket/ssl_client_socket_pool.cc

@@ -387,13 +387,6 @@ int SSLConnectJob::DoSSLConnectComplete(int result) {
                                  base::TimeDelta::FromMilliseconds(1),
                                  base::TimeDelta::FromMinutes(1), 100);
     }
-
-    if (ssl_info.dummy_pq_padding_received) {
-      UMA_HISTOGRAM_CUSTOM_TIMES("Net.SSL_Connection_Latency_PQPadding",
-                                 connect_duration,
-                                 base::TimeDelta::FromMilliseconds(1),
-                                 base::TimeDelta::FromMinutes(1), 100);
-    }
   }
 
   // Don't double-count the version interference probes.

net/ssl/ssl_info.h

@@ -108,11 +108,6 @@ class NET_EXPORT SSLInfo {
   // extension.
   TokenBindingParam token_binding_key_param = TB_PARAM_ECDSAP256;
 
-  // True if the server echoed a dummy post-quantum padding extension. See
-  // https://crbug.com/801302.
-  // TODO(agl): remove by 2018-05-31.
-  bool dummy_pq_padding_received = false;
-
   // True if data was received over early data on the server. This field is only
   // set for server sockets.
   bool early_data_received = false;

tools/metrics/histograms/histograms.xml

@@ -56625,6 +56625,9 @@ uploading your change for review.
 </histogram>
 
 <histogram name="Net.SSL_Connection_Latency_PQPadding" units="ms">
+  <obsolete>
+    Deprecated as of 2018-07-06.
+  </obsolete>
   <owner>agl@chromium.org</owner>
   <summary>
     Time from when the Connect() starts until it completes for any server that