Report better error message on update sandbox for gn builds

media/cast/sender/congestion_control.cc

Index: media/cast/sender/congestion_control.cc
diff --git a/media/cast/sender/congestion_control.cc b/media/cast/sender/congestion_control.cc
index bdf38dfd97e302a8e24dc00e04ef9e44b83a176a..4e4f19ce317a6b149d3b9f38f2b6688aadafe21a 100644
--- a/media/cast/sender/congestion_control.cc
+++ b/media/cast/sender/congestion_control.cc
@@ -18,6 +18,7 @@
 #include <deque>
 
 #include "base/logging.h"
+#include "base/trace_event/trace_event.h"
 #include "media/cast/cast_config.h"
 #include "media/cast/cast_defines.h"
 
@@ -367,6 +368,9 @@ uint32 AdaptiveCongestionControl::GetBitrate(base::TimeTicks playout_time,
   VLOG(3) << " FBR:" << (bits_per_second / 1E6)
           << " EBF:" << empty_buffer_fraction
           << " SBR:" << (safe_bitrate / 1E6);
+  TRACE_COUNTER_ID1("cast.stream", "Empty Buffer Fraction", this,
+                    empty_buffer_fraction);
+
   bits_per_second = std::max(bits_per_second, min_bitrate_configured_);
   bits_per_second = std::min(bits_per_second, max_bitrate_configured_);
   return bits_per_second;