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..a1bf2a85e950ac190de418b42d2c73f86068c0ad 100644
--- a/chrome/browser/net/ssl_config_service_manager_pref.cc
+++ b/chrome/browser/net/ssl_config_service_manager_pref.cc
@@ -23,11 +23,17 @@
 #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";
+const char* kGoogleDomain = "google.com";

[Alexei Svitkine (slow), 2015/02/06 20:26:34]

Nit: Change to the same syntax as the ones above, which is more efficient.

[jeremyim, 2015/02/06 22:40:29]

Done.

+
 // 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 +124,14 @@ void SSLConfigServicePref::GetSSLConfig(net::SSLConfig* config) {
   *config = cached_config_;
 }
 
+bool SSLConfigServicePref::SupportsFastradioPadding(const GURL& url) {
+  const std::string& host = url.host();
+  bool is_google =
+      host == kGoogleDomain ||
+      (host.size() > 10 && host.rfind(kGoogleDomain) == host.size() - 10);

[Alexei Svitkine (slow), 2015/02/06 20:26:34]

Can this use some of the existing utils we have in Chrome, such as
IsGoogleHostname()?

[Ryan Sleevi, 2015/02/06 22:12:59]

+1

[davidben, 2015/02/06 22:22:54]

If not switching it, note the current logic will trip on
"https://notgoogle.com". The suffix case should include the ., the equality case
should not.

[jeremyim, 2015/02/06 22:40:29]

Done.

+  return is_google;
+}
+
 void SSLConfigServicePref::SetNewSSLConfig(
     const net::SSLConfig& new_config) {
   net::SSLConfig orig_config = cached_config_;
@@ -286,6 +302,12 @@ 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)) {
+    config->enable_fastradio_padding = true;
+  }
 }
 
 void SSLConfigServiceManagerPref::OnDisabledCipherSuitesChange(