Read the number of TLs for VP9 too + cleanup

webrtc/video/screenshare_loopback.cc

Index: webrtc/video/screenshare_loopback.cc
diff --git a/webrtc/video/screenshare_loopback.cc b/webrtc/video/screenshare_loopback.cc
index 34f68947f660e84fc342196a019fa9778a1ec443..7ac35f4f31de64796cf406574a609b841ff30316 100644
--- a/webrtc/video/screenshare_loopback.cc
+++ b/webrtc/video/screenshare_loopback.cc
@@ -83,6 +83,11 @@ size_t TLDiscardThreshold() {
   return static_cast<size_t>(FLAGS_tl_discard_threshold);
 }
 
+DEFINE_bool(disable_wrapper_frame_dropper,
+            false,
+            "Disable FrameDropper in the wrapper. "
+            "Does not affect drop on capture or PacedSender.");
+
 DEFINE_int32(min_transmit_bitrate, 400, "Min transmit bitrate incl. padding.");
 int MinTransmitBitrateKbps() {
   return FLAGS_min_transmit_bitrate;
@@ -172,6 +177,7 @@ void Loopback() {
         flags::Codec(),
         flags::NumTemporalLayers(),
         flags::MinTransmitBitrateKbps() * 1000,
+        flags::FLAGS_disable_wrapper_frame_dropper,
         call_bitrate_config,
         flags::TLDiscardThreshold()
       },