Add AlrDetector

webrtc/modules/congestion_controller/alr_detector.h

Index: webrtc/modules/congestion_controller/alr_detector.h
diff --git a/webrtc/modules/congestion_controller/alr_detector.h b/webrtc/modules/congestion_controller/alr_detector.h
new file mode 100644
index 0000000000000000000000000000000000000000..9e9ec0593f68e1ac32cf81d604b24bb5128833a3
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+++ b/webrtc/modules/congestion_controller/alr_detector.h
@@ -0,0 +1,49 @@
+/*
+ *  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.
+ */
+
+#ifndef WEBRTC_MODULES_CONGESTION_CONTROLLER_ALR_DETECTOR_H_
+#define WEBRTC_MODULES_CONGESTION_CONTROLLER_ALR_DETECTOR_H_
+
+#include "webrtc/common_types.h"
+#include "webrtc/modules/pacing/paced_sender.h"
+#include "webrtc/typedefs.h"
+
+namespace webrtc {
+
+// Application limited region detector is a class that utilizes signals of
+// elapsed time and bytes sent to estimate whether network traffic is
+// currently limited by the application's ability to generate traffic.
+//
+// AlrDetector provides a signal that can be utilized to adjust
+// estimate bandwidth.
+// Note: This class is not thread-safe.
+class AlrDetector : public PacedSender::PacingObserver {
+ public:
+  AlrDetector();
+  ~AlrDetector();
+  // PacingObserver override.
+  void OnBytesSent(size_t bytes_sent, int64_t elapsed_time_ms) override;
+  // Set current estimated bandwidth.
+  void SetEstimatedBitrate(int bitrate_bps);
+  // Returns true if currently in application-limited region.
+  bool InApplicationLimitedRegion();
+
+ private:
+  int measurement_interval_bytes_sent_;
+  int64_t measurement_interval_elapsed_time_ms_;
+  int estimated_bitrate_bps_;
+  // Number of consecutive periods over which we observe traffic is application
+  // limited.
+  int application_limited_count_;
+};
+
+}  // namespace webrtc
+
+#endif  // WEBRTC_MODULES_CONGESTION_CONTROLLER_ALR_DETECTOR_H_