Add support for GCM cipher suites from RFC 7714.

webrtc/pc/channelmanager.cc

Index: webrtc/pc/channelmanager.cc
diff --git a/webrtc/pc/channelmanager.cc b/webrtc/pc/channelmanager.cc
index c2ce1cc604e941360b8e56962e95ce809f429f18..6f49a33b7862e2ad192c021d25fcfb5f4c3dc831 100644
--- a/webrtc/pc/channelmanager.cc
+++ b/webrtc/pc/channelmanager.cc
@@ -64,6 +64,7 @@ void ChannelManager::Construct(MediaEngineInterface* me,
   network_thread_ = network_thread;
   capturing_ = false;
   enable_rtx_ = false;
+  crypto_options_ = rtc::CryptoOptions::NoGcm();
 }
 
 ChannelManager::~ChannelManager() {
@@ -97,6 +98,22 @@ bool ChannelManager::SetVideoRtxEnabled(bool enable) {
   }
 }
 
+bool ChannelManager::SetCryptoOptions(
+    const rtc::CryptoOptions& crypto_options) {
+  return worker_thread_->Invoke<bool>(RTC_FROM_HERE, Bind(
+      &ChannelManager::SetCryptoOptions_w, this, crypto_options));
+}
+
+bool ChannelManager::SetCryptoOptions_w(
+    const rtc::CryptoOptions& crypto_options) {
+  if (!video_channels_.empty() || !voice_channels_.empty() ||
+      !data_channels_.empty()) {
+    LOG(LS_WARNING) << "Not changing crypto options in existing channels.";
+  }
+  crypto_options_ = crypto_options;
+  return true;
+}
+
 void ChannelManager::GetSupportedAudioSendCodecs(
     std::vector<AudioCodec>* codecs) const {
   *codecs = media_engine_->audio_send_codecs();
@@ -218,6 +235,7 @@ VoiceChannel* ChannelManager::CreateVoiceChannel_w(
   VoiceChannel* voice_channel =
       new VoiceChannel(worker_thread_, network_thread_, media_engine_.get(),
                        media_channel, transport_controller, content_name, rtcp);
+  voice_channel->SetCryptoOptions(crypto_options_);
   if (!voice_channel->Init_w(bundle_transport_name)) {
     delete voice_channel;
     return nullptr;
@@ -281,6 +299,7 @@ VideoChannel* ChannelManager::CreateVideoChannel_w(
   VideoChannel* video_channel =
       new VideoChannel(worker_thread_, network_thread_, media_channel,
                        transport_controller, content_name, rtcp);
+  video_channel->SetCryptoOptions(crypto_options_);
   if (!video_channel->Init_w(bundle_transport_name)) {
     delete video_channel;
     return NULL;
@@ -344,6 +363,7 @@ DataChannel* ChannelManager::CreateDataChannel_w(
   DataChannel* data_channel =
       new DataChannel(worker_thread_, network_thread_, media_channel,
                       transport_controller, content_name, rtcp);
+  data_channel->SetCryptoOptions(crypto_options_);
   if (!data_channel->Init_w(bundle_transport_name)) {
     LOG(LS_WARNING) << "Failed to init data channel.";
     delete data_channel;