Add interval estimator to remote bitrate estimator

webrtc/modules/remote_bitrate_estimator/probing_interval_estimator.cc

+/*
+ *  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/remote_bitrate_estimator/probing_interval_estimator.h"
+
+#include <algorithm>
+#include <utility>
+
+namespace webrtc {
+
+namespace {
+constexpr int kMinIntervalMs = 2000;
+constexpr int kMaxIntervalMs = 50000;
+}
+
+ProbingIntervalEstimator::ProbingIntervalEstimator(
+    const AimdRateControl* const aimd_rate_control)
+    : ProbingIntervalEstimator(kMinIntervalMs,
+                               kMaxIntervalMs,
+                               aimd_rate_control) {}
+
+ProbingIntervalEstimator::ProbingIntervalEstimator(
+    int min_interval_ms,
+    int max_interval_ms,
+    const AimdRateControl* const 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 {
+  auto drop_hight = aimd_rate_control_->GetLastDecrease();

[stefan-webrtc, 2016/10/26 14:30:06]

drop_height

I would also prefer not using auto for this fairly simple type.

+  auto increase_rate = aimd_rate_control_->GetNearMaxIncreaseRate();
+  if (drop_hight && increase_rate && *increase_rate > 0) {
+    return rtc::Optional<int>(std::min(
+        max_interval_ms_,
+        std::max(1000 * (*drop_hight) / (*increase_rate), min_interval_ms_)));
+  }
+  return rtc::Optional<int>();

[stefan-webrtc, 2016/10/26 14:30:06]

Have the "expected path" return here instead.

so basically:
if (!drop_height || !increase_rate || *increase_rate <= 0)
  return ...;

return ...;

+}
+
+}  // namespace webrtc