Add TransportFeedbackPacketLossTracker.

webrtc/modules/rtp_rtcp/source/rtcp_packet/transport_feedback.h

 /*
  *  Copyright (c) 2015 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_RTP_RTCP_SOURCE_RTCP_PACKET_TRANSPORT_FEEDBACK_H_
 #define WEBRTC_MODULES_RTP_RTCP_SOURCE_RTCP_PACKET_TRANSPORT_FEEDBACK_H_
 
 #include <memory>
 #include <vector>
 
 #include "webrtc/base/constructormagic.h"
 #include "webrtc/modules/rtp_rtcp/source/rtcp_packet/rtpfb.h"
 
 namespace webrtc {
 namespace rtcp {
+
+class TransportFeedbackInterface {

[minyue-webrtc, 2017/01/19 11:11:45]

Hi Erik,

I would like you take a look at my way of abstracting TransportFeedback. I may
include more (or less) APIs than necessary. 

+ public:
+  virtual ~TransportFeedbackInterface() = default;
+  enum class StatusSymbol {
+    kNotReceived,
+    kReceivedSmallDelta,
+    kReceivedLargeDelta,
+  };
+  virtual void SetBase(uint16_t base_sequence, int64_t ref_timestamp_us) = 0;
+  virtual void SetFeedbackSequenceNumber(uint8_t feedback_sequence) = 0;
+  virtual bool AddReceivedPacket(uint16_t sequence_number,
+                                 int64_t timestamp_us) = 0;
+  virtual uint16_t GetBaseSequence() const = 0;
+  virtual std::vector<StatusSymbol> GetStatusVector() const = 0;
+  virtual std::vector<int16_t> GetReceiveDeltas() const = 0;
+  virtual int64_t GetBaseTimeUs() const = 0;
+  virtual std::vector<int64_t> GetReceiveDeltasUs() const = 0;
+};
+
 class CommonHeader;
 
-class TransportFeedback : public Rtpfb {
+// TODO(minyue): Update PacketCounter so that TransportFeedback can become a
+// final class.
+class TransportFeedback : public Rtpfb, public TransportFeedbackInterface {
  public:
   class ReceivedPacket {
    public:
     ReceivedPacket(uint16_t sequence_number, int16_t delta_ticks)
         : sequence_number_(sequence_number), delta_ticks_(delta_ticks) {}
     ReceivedPacket(const ReceivedPacket&) = default;
     ReceivedPacket& operator=(const ReceivedPacket&) = default;
 
     uint16_t sequence_number() const { return sequence_number_; }
     int16_t delta_ticks() const { return delta_ticks_; }
     int32_t delta_us() const { return delta_ticks_ * kDeltaScaleFactor; }
 
    private:
     uint16_t sequence_number_;
     int16_t delta_ticks_;
   };
   // TODO(sprang): IANA reg?
   static constexpr uint8_t kFeedbackMessageType = 15;
   // Convert to multiples of 0.25ms.
   static constexpr int kDeltaScaleFactor = 250;
   // Maximum number of packets (including missing) TransportFeedback can report.
   static constexpr size_t kMaxReportedPackets = 0xffff;
 
   TransportFeedback();
   ~TransportFeedback() override;
 
-  void SetBase(uint16_t base_sequence,     // Seq# of first packet in this msg.
-               int64_t ref_timestamp_us);  // Reference timestamp for this msg.
-  void SetFeedbackSequenceNumber(uint8_t feedback_sequence);
+  void SetBase(uint16_t base_sequence,    // Seq# of first packet in this msg.
+               int64_t ref_timestamp_us)  // Reference timestamp for this msg.
+      override;
+  void SetFeedbackSequenceNumber(uint8_t feedback_sequence) override;
   // NOTE: This method requires increasing sequence numbers (excepting wraps).
-  bool AddReceivedPacket(uint16_t sequence_number, int64_t timestamp_us);
-  const std::vector<ReceivedPacket>& GetReceivedPackets() const;
+  bool AddReceivedPacket(uint16_t sequence_number,
+                         int64_t timestamp_us) override;
 
-  enum class StatusSymbol {
-    kNotReceived,
-    kReceivedSmallDelta,
-    kReceivedLargeDelta,
-  };
-
-  uint16_t GetBaseSequence() const;
-  std::vector<TransportFeedback::StatusSymbol> GetStatusVector() const;
-  std::vector<int16_t> GetReceiveDeltas() const;
+  uint16_t GetBaseSequence() const override;
+  std::vector<StatusSymbol> GetStatusVector() const override;
+  std::vector<int16_t> GetReceiveDeltas() const override;
 
   // Get the reference time in microseconds, including any precision loss.
-  int64_t GetBaseTimeUs() const;
+  int64_t GetBaseTimeUs() const override;
   // Convenience method for getting all deltas as microseconds. The first delta
   // is relative the base time.
-  std::vector<int64_t> GetReceiveDeltasUs() const;
+  std::vector<int64_t> GetReceiveDeltasUs() const override;
 
   bool Parse(const CommonHeader& packet);
   static std::unique_ptr<TransportFeedback> ParseFrom(const uint8_t* buffer,
                                                       size_t length);
   // Pre and postcondition for all public methods. Should always return true.
   // This function is for tests.
   bool IsConsistent() const;
+  const std::vector<ReceivedPacket>& GetReceivedPackets() const;
 
  protected:
   bool Create(uint8_t* packet,
               size_t* position,
               size_t max_length,
               PacketReadyCallback* callback) const override;
 
   size_t BlockLength() const override;
 
  private:
@@ skipping 19 matching lines @@
   std::vector<uint16_t> encoded_chunks_;
   const std::unique_ptr<LastChunk> last_chunk_;
   size_t size_bytes_;
 
   RTC_DISALLOW_COPY_AND_ASSIGN(TransportFeedback);
 };
 
 }  // namespace rtcp
 }  // namespace webrtc
 #endif  // WEBRTC_MODULES_RTP_RTCP_SOURCE_RTCP_PACKET_TRANSPORT_FEEDBACK_H_