Plumbing for TCP FastOpen field trial and enables it for SSL sockets.

chrome/browser/io_thread.cc

Index: chrome/browser/io_thread.cc
diff --git a/chrome/browser/io_thread.cc b/chrome/browser/io_thread.cc
index d055905183c0c87199ed2c58cad7d1e4a2daba0f..4109850b005c3776160b7cdaf0acd867755a85e7 100644
--- a/chrome/browser/io_thread.cc
+++ b/chrome/browser/io_thread.cc
@@ -115,6 +115,8 @@ class SafeBrowsingURLRequestContext;
 
 namespace {
 
+const char kTCPFastOpenForSSLFieldTrialName[] = "TCPFastOpenEnabledForSSL";
+
 const char kQuicFieldTrialName[] = "QUIC";
 const char kQuicFieldTrialEnabledGroupName[] = "Enabled";
 const char kQuicFieldTrialHttpsEnabledGroupName[] = "HttpsEnabled";
@@ -839,13 +841,21 @@ void IOThread::InitializeNetworkOptions(const CommandLine& command_line) {
       globals_->enable_websocket_over_spdy.set(true);
   }
 
+  ConfigureTCPFastOpen(command_line);
+
   // TODO(rch): Make the client socket factory a per-network session
   // instance, constructed from a NetworkSession::Params, to allow us
   // to move this option to IOThread::Globals &
   // HttpNetworkSession::Params.
+}
 
+void IOThread::ConfigureTCPFastOpen(const CommandLine& command_line) {
+  const std::string trial_group =
+      base::FieldTrialList::FindFullName(kTCPFastOpenForSSLFieldTrialName);
+  if (trial_group == kTCPFastOpenForSSLFieldTrialName)
+    globals_->enable_tcp_fast_open_for_ssl.set(true);

[Randy Smith (Not in Mondays), 2014/09/10 18:57:06]

This looks wrong to me--it looks like you're conflating the field trial name
with the group within the trial that you're going to use.  Usually field trials
have 3 groups: Enabled/Disabled/Default (often named just that) and you select
among them.  You can take a look at how I'm doing SDCH in chrome_browser_main.cc
(search for "SDCH" to see what I mean.

More generally, I'd recommend you do the finch bug to setup a field trial, get a
finch ambassador assigned, and ask them to review this CL.  They often have
preferences about how you do things, and catching them earlier rather than later
is helpful.

[Jana, 2014/09/11 20:04:59]

Yes, you are right -- I had conflated these things. I've separated them out, now
that I (yet again) understand Finch better. PTAL.

   bool always_enable_if_supported =
-    command_line.HasSwitch(switches::kEnableTcpFastOpen);
+      command_line.HasSwitch(switches::kEnableTcpFastOpen);
   // Check for OS support of TCP FastOpen, and turn it on for all connections
   // if indicated by user.
   net::CheckSupportAndMaybeEnableTCPFastOpen(always_enable_if_supported);
@@ -1014,6 +1024,8 @@ void IOThread::InitializeNetworkSessionParamsFromGlobals(
   params->ignore_certificate_errors = globals.ignore_certificate_errors;
   params->testing_fixed_http_port = globals.testing_fixed_http_port;
   params->testing_fixed_https_port = globals.testing_fixed_https_port;
+  globals.enable_tcp_fast_open_for_ssl.CopyToIfSet(
+      &params->enable_tcp_fast_open_for_ssl);
 
   globals.initial_max_spdy_concurrent_streams.CopyToIfSet(
       &params->spdy_initial_max_concurrent_streams);