Tweaked version of BBR for WebRTC.

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 c6695e9311e9a40d037f1c30399390e9451cd7dc..f479e52d763f5e24cdbbf899387b356295838b3f 100644
--- a/webrtc/modules/bitrate_controller/include/bitrate_controller.h
+++ b/webrtc/modules/bitrate_controller/include/bitrate_controller.h
@@ -15,6 +15,8 @@
 #ifndef WEBRTC_MODULES_BITRATE_CONTROLLER_INCLUDE_BITRATE_CONTROLLER_H_
 #define WEBRTC_MODULES_BITRATE_CONTROLLER_INCLUDE_BITRATE_CONTROLLER_H_
 
+#include <map>
+
 #include "webrtc/modules/congestion_controller/delay_based_bwe.h"
 #include "webrtc/modules/include/module.h"
 #include "webrtc/modules/pacing/paced_sender.h"
@@ -36,12 +38,18 @@ class BitrateObserver {
   virtual void OnNetworkChanged(uint32_t bitrate_bps,
                                 uint8_t fraction_loss,  // 0 - 255.
                                 int64_t rtt_ms) = 0;
-
+  // TODO(gnish): Merge these two into one function.
+  virtual void OnNetworkChanged(uint32_t bitrate_for_encoder_bps,
+                                uint32_t bitrate_for_pacer_bps,
+                                bool in_probe_rtt,
+                                int64_t target_set_time,
+                                uint64_t congestion_window) {}
+  virtual void OnBytesAcked(size_t bytes) {}
+  virtual size_t pacer_queue_size_in_bytes() { return 0; }
   virtual ~BitrateObserver() {}
 };
 
-class BitrateController : public Module,
-                          public RtcpBandwidthObserver {
+class BitrateController : public Module, public RtcpBandwidthObserver {
   // This class collects feedback from all streams sent to a peer (via
   // RTCPBandwidthObservers). It does one  aggregated send side bandwidth
   // estimation and divide the available bitrate between all its registered