Update to current webrtc library

This is from the upstream library commit id
3326535126e435f1ba647885ce43a8f0f3d317eb, corresponding to Chromium
88.0.4290.1.

webrtc/api/call/bitrate_allocation.h

@@ -0,0 +1,45 @@
+/*
+ *  Copyright 2018 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+#ifndef API_CALL_BITRATE_ALLOCATION_H_
+#define API_CALL_BITRATE_ALLOCATION_H_
+
+#include "api/units/data_rate.h"
+#include "api/units/time_delta.h"
+
+namespace webrtc {
+
+// BitrateAllocationUpdate provides information to allocated streams about their
+// bitrate allocation. It originates from the BitrateAllocater class and is
+// propagated from there.
+struct BitrateAllocationUpdate {
+  // The allocated target bitrate. Media streams should produce this amount of
+  // data. (Note that this may include packet overhead depending on
+  // configuration.)
+  DataRate target_bitrate = DataRate::Zero();
+  // The allocated part of the estimated link capacity. This is more stable than
+  // the target as it is based on the underlying link capacity estimate. This
+  // should be used to change encoder configuration when the cost of change is
+  // high.
+  DataRate stable_target_bitrate = DataRate::Zero();
+  // Predicted packet loss ratio.
+  double packet_loss_ratio = 0;
+  // Predicted round trip time.
+  TimeDelta round_trip_time = TimeDelta::PlusInfinity();
+  // |bwe_period| is deprecated, use |stable_target_bitrate| allocation instead.
+  TimeDelta bwe_period = TimeDelta::PlusInfinity();
+  // Congestion window pushback bitrate reduction fraction. Used in
+  // VideoStreamEncoder to reduce the bitrate by the given fraction
+  // by dropping frames.
+  double cwnd_reduce_ratio = 0;
+};
+
+}  // namespace webrtc
+
+#endif  // API_CALL_BITRATE_ALLOCATION_H_