Periodically update channel parameters and send TargetBitrate message.

webrtc/video/vie_encoder.cc

Index: webrtc/video/vie_encoder.cc
diff --git a/webrtc/video/vie_encoder.cc b/webrtc/video/vie_encoder.cc
index adf8fe7eb4677a9e497b4292e8a7e244fe354b9f..b1b1114ae234ac3ff25ecdf994090100ce8eefe5 100644
--- a/webrtc/video/vie_encoder.cc
+++ b/webrtc/video/vie_encoder.cc
@@ -547,9 +547,16 @@ void ViEEncoder::EncodeVideoFrame(const VideoFrame& video_frame,
                  << ", texture=" << last_frame_info_->is_texture;
   }
 
+  int64_t now_ms = clock_->TimeInMilliseconds();
   if (pending_encoder_reconfiguration_) {
     ReconfigureEncoder();
+  } else if (!last_parameters_update_ms_ ||
+             now_ms - *last_parameters_update_ms_ >=
+                 vcm::VCMProcessTimer::kDefaultProcessIntervalMs) {
+    video_sender_.UpdateChannelParemeters(rate_allocator_.get(),
+                                          bitrate_observer_);
   }
+  last_parameters_update_ms_.emplace(now_ms);
 
   if (EncoderPaused()) {
     TraceFrameDropStart();