Perform ClientHello padding if the field trial is enabled

chrome/browser/net/ssl_config_service_manager_pref.cc

Index: chrome/browser/net/ssl_config_service_manager_pref.cc
diff --git a/chrome/browser/net/ssl_config_service_manager_pref.cc b/chrome/browser/net/ssl_config_service_manager_pref.cc
index decd8951c11ef5829b8125a65b5634150749d906..0190be44b876ffd7b6d29640412998835fab89d1 100644
--- a/chrome/browser/net/ssl_config_service_manager_pref.cc
+++ b/chrome/browser/net/ssl_config_service_manager_pref.cc
@@ -19,15 +19,21 @@
 #include "chrome/common/pref_names.h"
 #include "components/content_settings/core/browser/content_settings_utils.h"
 #include "components/content_settings/core/common/content_settings.h"
+#include "components/google/core/browser/google_util.h"
 #include "content/public/browser/browser_thread.h"
 #include "net/socket/ssl_client_socket.h"
 #include "net/ssl/ssl_cipher_suite_names.h"
 #include "net/ssl/ssl_config_service.h"
+#include "url/gurl.h"
 
 using content::BrowserThread;
 
 namespace {
 
+// Field trial for ClientHello padding.
+const char kClientHelloFieldTrialName[] = "FastRadioPadding";
+const char kClientHelloFieldTrialEnabledGroupName[] = "Enabled";
+
 // Converts a ListValue of StringValues into a vector of strings. Any Values
 // which cannot be converted will be skipped.
 std::vector<std::string> ListValueToStringVector(const base::ListValue* value) {
@@ -96,6 +102,8 @@ class SSLConfigServicePref : public net::SSLConfigService {
   // Store SSL config settings in |config|. Must only be called from IO thread.
   void GetSSLConfig(net::SSLConfig* config) override;
 
+  bool SupportsFastradioPadding(const GURL& url) override;
+
  private:
   // Allow the pref watcher to update our internal state.
   friend class SSLConfigServiceManagerPref;
@@ -116,6 +124,11 @@ void SSLConfigServicePref::GetSSLConfig(net::SSLConfig* config) {
   *config = cached_config_;
 }
 
+bool SSLConfigServicePref::SupportsFastradioPadding(const GURL& url) {

[Ryan Sleevi, 2015/02/09 19:42:34]

Should this be FastRadioPadding? "fastradio" isn't one word, is it?

[jeremyim, 2015/02/09 21:32:15]

The BoringSSL function is SSL_enable_fastradio_padding, which implies that it is
one word.

+  return google_util::IsGoogleHostname(url.host(),
+                                       google_util::ALLOW_SUBDOMAIN);
+}
+
 void SSLConfigServicePref::SetNewSSLConfig(
     const net::SSLConfig& new_config) {
   net::SSLConfig orig_config = cached_config_;
@@ -286,6 +299,12 @@ void SSLConfigServiceManagerPref::GetSSLConfigFromPrefs(
   config->disabled_cipher_suites = disabled_cipher_suites_;
   // disabling False Start also happens to disable record splitting.
   config->false_start_enabled = !ssl_record_splitting_disabled_.GetValue();
+
+  base::StringPiece group =
+      base::FieldTrialList::FindFullName(kClientHelloFieldTrialName);
+  if (group.starts_with(kClientHelloFieldTrialEnabledGroupName)) {

[Ryan Sleevi, 2015/02/09 19:42:34]

Why is this .starts_with and not ==?

[jeremyim, 2015/02/09 21:32:15]

In case there is a reason to have multiple "Enabled" experiment groups; at least
in io_thread.cc the usage seems to be split between starts_with and ==.

+    config->fastradio_padding_enabled = true;
+  }
 }
 
 void SSLConfigServiceManagerPref::OnDisabledCipherSuitesChange(