Add support for GCM cipher suites from RFC 7714.

webrtc/p2p/base/transportcontroller.cc

Index: webrtc/p2p/base/transportcontroller.cc
diff --git a/webrtc/p2p/base/transportcontroller.cc b/webrtc/p2p/base/transportcontroller.cc
index 22b827a1a5ac2bda29b14296788b15a24824ec33..f32ce38647cdbc0454c739f46ef92dabba480a14 100644
--- a/webrtc/p2p/base/transportcontroller.cc
+++ b/webrtc/p2p/base/transportcontroller.cc
@@ -56,6 +56,11 @@ bool TransportController::SetSslMaxProtocolVersion(
       &TransportController::SetSslMaxProtocolVersion_w, this, version));
 }
 
+bool TransportController::SetEnableGcmCiphers(bool enable) {
+  return worker_thread_->Invoke<bool>(rtc::Bind(
+      &TransportController::SetEnableGcmCiphers_w, this, enable));
+}
+
 void TransportController::SetIceConfig(const IceConfig& config) {
   worker_thread_->Invoke<void>(
       rtc::Bind(&TransportController::SetIceConfig_w, this, config));
@@ -283,6 +288,7 @@ Transport* TransportController::GetOrCreateTransport_w(
   // The stuff below happens outside of CreateTransport_w so that unit tests
   // can override CreateTransport_w to return a different type of transport.
   transport->SetSslMaxProtocolVersion(ssl_max_version_);
+  transport->SetEnableGcmCiphers(enable_gcm_ciphers_);
   transport->SetIceConfig(ice_config_);
   transport->SetIceRole(ice_role_);
   transport->SetIceTiebreaker(ice_tiebreaker_);
@@ -327,6 +333,18 @@ bool TransportController::SetSslMaxProtocolVersion_w(
   return true;
 }
 
+bool TransportController::SetEnableGcmCiphers_w(bool enable) {
+  RTC_DCHECK(worker_thread_->IsCurrent());
+
+  // GCM ciphers can only be enabled before transports are created.
+  if (!transports_.empty()) {
+    return false;
+  }
+
+  enable_gcm_ciphers_ = enable;
+  return true;
+}
+
 void TransportController::SetIceConfig_w(const IceConfig& config) {
   RTC_DCHECK(worker_thread_->IsCurrent());
   ice_config_ = config;