Added protobuf message for loss-based BWE events, and wired it up to the send side bandwidth estima…

webrtc/call/rtc_event_log.h

Index: webrtc/call/rtc_event_log.h
diff --git a/webrtc/call/rtc_event_log.h b/webrtc/call/rtc_event_log.h
index 85d752575244194a3de9fe20385474cf84e3488b..489687a1953d64237b706d9237aae66005c76ca2 100644
--- a/webrtc/call/rtc_event_log.h
+++ b/webrtc/call/rtc_event_log.h
@@ -77,6 +77,11 @@ class RtcEventLog {
   // Logs an audio playout event
   virtual void LogAudioPlayout(uint32_t ssrc) = 0;
 
+  // Logs a bitrate update from the bandwidth estimator based on packet loss.
+  virtual void LogBwePacketLossEvent(int32_t bitrate,
+                                     uint8_t fraction_loss,
+                                     int32_t total_packets) = 0;
+
   // Reads an RtcEventLog file and returns true when reading was successful.
   // The result is stored in the given EventStream object.
   static bool ParseRtcEventLog(const std::string& file_name,