Add FullStack test for simulcast screenshare mode.

webrtc/modules/video_coding/codecs/vp8/simulcast_rate_allocator.cc

Index: webrtc/modules/video_coding/codecs/vp8/simulcast_rate_allocator.cc
diff --git a/webrtc/modules/video_coding/codecs/vp8/simulcast_rate_allocator.cc b/webrtc/modules/video_coding/codecs/vp8/simulcast_rate_allocator.cc
index af073cd370f70c84b9cf56b61531a4550cacfa52..4cacabf442f7393e45f07005b6740c7a64c85c71 100644
--- a/webrtc/modules/video_coding/codecs/vp8/simulcast_rate_allocator.cc
+++ b/webrtc/modules/video_coding/codecs/vp8/simulcast_rate_allocator.cc
@@ -30,6 +30,7 @@ SimulcastRateAllocator::SimulcastRateAllocator(
 void SimulcastRateAllocator::OnTemporalLayersCreated(int simulcast_id,
                                                      TemporalLayers* layers) {
   RTC_DCHECK(temporal_layers_.find(simulcast_id) == temporal_layers_.end());
+  RTC_DCHECK(layers != nullptr);

[stefan-webrtc, 2017/03/09 14:07:46]

I think you can omit nullptr

[ilnik, 2017/03/09 14:34:35]

Done.

   temporal_layers_[simulcast_id] = layers;
 }