Add UMA metrics and finch experiment for DTLS1.2 in WebRTC.

content/renderer/media/webrtc/peer_connection_dependency_factory.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "content/renderer/media/webrtc/peer_connection_dependency_factory.h"
 
 #include <vector>
 
 #include "base/command_line.h"
 #include "base/location.h"
@@ skipping 389 matching lines @@
 
   pc_factory_ = webrtc::CreatePeerConnectionFactory(
       worker_thread_, signaling_thread_, audio_device_.get(),
       encoder_factory.release(), decoder_factory.release());
   CHECK(pc_factory_.get());
 
   webrtc::PeerConnectionFactoryInterface::Options factory_options;
   factory_options.disable_sctp_data_channels = false;
   factory_options.disable_encryption =
       cmd_line->HasSwitch(switches::kDisableWebRtcEncryption);
-  if (cmd_line->HasSwitch(switches::kEnableWebRtcDtls12))
+
+  std::string group_name =
+      base::FieldTrialList::FindFullName("WebRTC-PeerConnectionDTLS1.2");
+  if (StartsWith(group_name, "Enabled", base::CompareCase::SENSITIVE) ||
+      cmd_line->HasSwitch(switches::kEnableWebRtcDtls12)) {
     factory_options.ssl_max_version = rtc::SSL_PROTOCOL_DTLS_12;
+  }
   pc_factory_->SetOptions(factory_options);
 
   event->Signal();
 }
 
 bool PeerConnectionDependencyFactory::PeerConnectionFactoryCreated() {
   return pc_factory_.get() != NULL;
 }
 
 scoped_refptr<webrtc::PeerConnectionInterface>
@@ skipping 327 matching lines @@
 }
 
 void PeerConnectionDependencyFactory::EnsureWebRtcAudioDeviceImpl() {
   if (audio_device_.get())
     return;
 
   audio_device_ = new WebRtcAudioDeviceImpl();
 }
 
 }  // namespace content