Add content type extension to capabilities

webrtc/media/engine/webrtcvideoengine2.cc

 /*
  *  Copyright (c) 2014 The WebRTC project authors. All Rights Reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
@@ skipping 31 matching lines @@
 
 namespace cricket {
 namespace {
 // If this field trial is enabled, we will enable sending FlexFEC and disable
 // sending ULPFEC whenever the former has been negotiated. Receiving FlexFEC
 // is enabled whenever FlexFEC has been negotiated.
 bool IsFlexfecFieldTrialEnabled() {
   return webrtc::field_trial::FindFullName("WebRTC-FlexFEC-03") == "Enabled";
 }
 
+bool IsVideoContentTypeExtensionEnabled() {

[brandtr, 2017/04/13 09:42:50]

Nits:

1) Add "FieldTrial" to the name of this function, so it's clear on line 511 that
this extension is gated behind a field trial.
2) Above this function, add a comment describing what happens when this field
trial is enabled.

[ilnik, 2017/04/13 09:47:44]

Done.

+  return webrtc::field_trial::FindFullName(
+             "WebRTC-VideoContentTypeExtension") == "Enabled";

[brandtr, 2017/04/13 09:42:50]

Replace with a call to this function instead:
https://cs.chromium.org/chromium/src/third_party/webrtc/system_wrappers/inclu....

Can explain offline.

[ilnik, 2017/04/13 09:47:44]

Done.

+}
+
 // Wrap cricket::WebRtcVideoEncoderFactory as a webrtc::VideoEncoderFactory.
 class EncoderFactoryAdapter : public webrtc::VideoEncoderFactory {
  public:
   // EncoderFactoryAdapter doesn't take ownership of |factory|, which is owned
   // by e.g. PeerConnectionFactory.
   explicit EncoderFactoryAdapter(cricket::WebRtcVideoEncoderFactory* factory)
       : factory_(factory) {}
   virtual ~EncoderFactoryAdapter() {}
 
   // Implement webrtc::VideoEncoderFactory.
@@ skipping 434 matching lines @@
                            webrtc::RtpExtension::kAbsSendTimeDefaultId));
   capabilities.header_extensions.push_back(
       webrtc::RtpExtension(webrtc::RtpExtension::kVideoRotationUri,
                            webrtc::RtpExtension::kVideoRotationDefaultId));
   capabilities.header_extensions.push_back(webrtc::RtpExtension(
       webrtc::RtpExtension::kTransportSequenceNumberUri,
       webrtc::RtpExtension::kTransportSequenceNumberDefaultId));
   capabilities.header_extensions.push_back(
       webrtc::RtpExtension(webrtc::RtpExtension::kPlayoutDelayUri,
                            webrtc::RtpExtension::kPlayoutDelayDefaultId));
+  if (IsVideoContentTypeExtensionEnabled()) {
+    capabilities.header_extensions.push_back(
+        webrtc::RtpExtension(webrtc::RtpExtension::kVideoContentTypeUri,
+                             webrtc::RtpExtension::kVideoContentTypeDefaultId));
+  }
   return capabilities;
 }
 
 void WebRtcVideoEngine2::SetExternalDecoderFactory(
     WebRtcVideoDecoderFactory* decoder_factory) {
   RTC_DCHECK(!initialized_);
   external_decoder_factory_ = decoder_factory;
 }
 
 void WebRtcVideoEngine2::SetExternalEncoderFactory(
@@ skipping 2045 matching lines @@
         rtx_mapping[video_codecs[i].codec.id] !=
             ulpfec_config.red_payload_type) {
       video_codecs[i].rtx_payload_type = rtx_mapping[video_codecs[i].codec.id];
     }
   }
 
   return video_codecs;
 }
 
 }  // namespace cricket