Fix SetRates for encoders with internal sources.

webrtc/modules/video_coding/video_sender.cc

Index: webrtc/modules/video_coding/video_sender.cc
diff --git a/webrtc/modules/video_coding/video_sender.cc b/webrtc/modules/video_coding/video_sender.cc
index f14f8521148248507e3ff8048e8dadc708eb94cf..ae5bd6c6bb23566bcf724dfee929c8e07ec6b1fb 100644
--- a/webrtc/modules/video_coding/video_sender.cc
+++ b/webrtc/modules/video_coding/video_sender.cc
@@ -202,8 +202,22 @@ int32_t VideoSender::SetChannelParameters(uint32_t target_bitrate,
 
   uint32_t input_frame_rate = _mediaOpt.InputFrameRate();
 
-  rtc::CritScope cs(&params_crit_);
-  encoder_params_ = {target_rate, lossRate, rtt, input_frame_rate};
+  EncoderParameters encoder_params = {target_rate, lossRate, rtt,
+                                      input_frame_rate};
+  {
+    rtc::CritScope cs(&params_crit_);
+    encoder_params_ = encoder_params;
+  }
+
+  // For encoders with internal sources, we need to tell the encoder directly,
+  // instead of waiting for an AddVideoFrame that will never come (internal
+  // source encoders don't get input frames).
+  {
+    rtc::CritScope cs(&encoder_crit_);

[pbos-webrtc, 2016/02/11 10:17:00]

I believe that this lock could block (the network thread, perhaps?) during
encoder use. Can you see if we can cache _encoder->InteralSource() under the
params_crit_ so that we don't have to acquire this lock for non-internal-source?

+    if (_encoder && _encoder->InternalSource()) {
+      SetEncoderParameters(encoder_params);
+    }
+  }
 
   return VCM_OK;
 }