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

webrtc/modules/bitrate_controller/include/bitrate_controller.h

Index: webrtc/modules/bitrate_controller/include/bitrate_controller.h
diff --git a/webrtc/modules/bitrate_controller/include/bitrate_controller.h b/webrtc/modules/bitrate_controller/include/bitrate_controller.h
index 5b20287c636cd33a88edde6f331f92f9cb3146ce..d1eca8e0fe49431d89aa6ae6482ef828ecc4fc9e 100644
--- a/webrtc/modules/bitrate_controller/include/bitrate_controller.h
+++ b/webrtc/modules/bitrate_controller/include/bitrate_controller.h
@@ -23,6 +23,7 @@
 namespace webrtc {
 
 class CriticalSectionWrapper;
+class RtcEventLog;
 struct PacketInfo;
 
 class BitrateObserver {
@@ -56,6 +57,8 @@ class BitrateController : public Module {
   virtual void SetStartBitrate(int start_bitrate_bps) = 0;
   virtual void SetMinMaxBitrate(int min_bitrate_bps, int max_bitrate_bps) = 0;
 
+  virtual void SetEventLog(RtcEventLog* event_log) = 0;
+
   // Gets the available payload bandwidth in bits per second. Note that
   // this bandwidth excludes packet headers.
   virtual bool AvailableBandwidth(uint32_t* bandwidth) const = 0;