Add VideoTrackSource implementation.

webrtc/api/rtpsender.cc

Index: webrtc/api/rtpsender.cc
diff --git a/webrtc/api/rtpsender.cc b/webrtc/api/rtpsender.cc
index c5db92946d200ab0d643107cfa871fe4e6c519a6..f441b3fbc6ec2967a20f808d6108d9471dc93062 100644
--- a/webrtc/api/rtpsender.cc
+++ b/webrtc/api/rtpsender.cc
@@ -320,12 +320,14 @@ void VideoRtpSender::Stop() {
 
 void VideoRtpSender::SetVideoSend() {
   RTC_DCHECK(!stopped_ && can_send_track());
-  const cricket::VideoOptions* options = nullptr;
+  cricket::VideoOptions options;
   VideoTrackSourceInterface* source = track_->GetSource();
   if (track_->enabled() && source) {
-    options = source->options();
+    options.is_screencast = rtc::Optional<bool>(source->is_screencast());
+    options.video_noise_reduction =
+        rtc::Optional<bool>(source->needs_denoising());

[pthatcher1, 2016/03/08 21:27:31]

We should probably set these even when the track is not enabled (just check
if(source)).  That way, send parameters for screencasts that are disable and
re-enabled won't change dramatically in the process.

[perkj_webrtc, 2016/03/08 22:23:57]

ah right...

   }
-  provider_->SetVideoSend(ssrc_, track_->enabled(), options);
+  provider_->SetVideoSend(ssrc_, track_->enabled(), &options);
 }
 
 }  // namespace webrtc