Extract common simulcast logic from VP8 wrapper and simulcast adapter

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 91fc1f0db21ad80a32868185fcfba8273376f2c0..36ac9c57f0cef111493579d520b38a23bc51898a 100644
--- a/webrtc/video/vie_encoder.cc
+++ b/webrtc/video/vie_encoder.cc
@@ -433,6 +433,7 @@ void ViEEncoder::OnBitrateUpdated(uint32_t bitrate_bps,
                                      round_trip_time_ms);
   bool video_is_suspended = video_sender_.VideoSuspended();
   bool video_suspension_changed;
+
   {
     rtc::CritScope lock(&data_cs_);
     last_observed_bitrate_bps_ = bitrate_bps;