Add interval estimator to remote bitrate estimator

webrtc/modules/congestion_controller/probing_interval_estimator.cc

Index: webrtc/modules/congestion_controller/probing_interval_estimator.cc
diff --git a/webrtc/modules/congestion_controller/probing_interval_estimator.cc b/webrtc/modules/congestion_controller/probing_interval_estimator.cc
new file mode 100644
index 0000000000000000000000000000000000000000..ed1134737e6dc3294fbd0e53a9fa044da6ee60ce
--- /dev/null
+++ b/webrtc/modules/congestion_controller/probing_interval_estimator.cc
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+/*
+ *  Copyright (c) 2016 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.
+ */
+
+#include "webrtc/modules/congestion_controller/probing_interval_estimator.h"
+
+#include <algorithm>
+#include <utility>
+
+namespace webrtc {
+
+namespace {
+constexpr int kMinIntervalMs = 2000;
+constexpr int kMaxIntervalMs = 50000;
+}
+
+ProbingIntervalEstimator::ProbingIntervalEstimator(
+    const AimdRateControl* aimd_rate_control)
+    : ProbingIntervalEstimator(kMinIntervalMs,
+                               kMaxIntervalMs,
+                               aimd_rate_control) {}
+
+ProbingIntervalEstimator::ProbingIntervalEstimator(
+    int min_interval_ms,
+    int max_interval_ms,
+    const AimdRateControl* aimd_rate_control)
+    : min_interval_ms_(min_interval_ms),
+      max_interval_ms_(max_interval_ms),
+      aimd_rate_control_(aimd_rate_control) {}
+
+rtc::Optional<int> ProbingIntervalEstimator::GetIntervalMs() const {
+  rtc::Optional<int> bitrate_drop =
+      aimd_rate_control_->GetLastBitrateDecreaseBps();
+  int increase_rate = aimd_rate_control_->GetNearMaxIncreaseRateBps();
+
+  if (!bitrate_drop || increase_rate <= 0)
+    return rtc::Optional<int>();
+
+  return rtc::Optional<int>(std::min(
+      max_interval_ms_,
+      std::max(1000 * (*bitrate_drop) / increase_rate, min_interval_ms_)));
+}
+
+}  // namespace webrtc