Avoid circular dependency rtp_rtcp <-> paced_sender

webrtc/modules/rtp_rtcp/interface/rtp_rtcp_defines.h

 /*
  *  Copyright (c) 2012 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.
  */
 
@@ skipping 377 matching lines @@
   // The number of packets lost in events where no adjacent packets were also
   // lost.
   uint64_t single_packet_loss_count;
   // The number of events in which more than one adjacent packet was lost.
   uint64_t multiple_packet_loss_event_count;
   // The number of packets lost in events where more than one adjacent packet
   // was lost.
   uint64_t multiple_packet_loss_packet_count;
 };
 
+class RtpPacketSender {
+ public:
+  RtpPacketSender() {}
+  virtual ~RtpPacketSender() {}
+
+  enum Priority {
+    kHighPriority = 0,    // Pass through; will be sent immediately.
+    kNormalPriority = 2,  // Put in back of the line.
+    kLowPriority = 3,     // Put in back of the low priority line.
+  };
+  // Low priority packets are mixed with the normal priority packets
+  // while we are paused.
+
+  // Returns true if we send the packet now, else it will add the packet
+  // information to the queue and call TimeToSendPacket when it's time to send.
+  virtual bool SendPacket(Priority priority,
+                          uint32_t ssrc,
+                          uint16_t sequence_number,
+                          int64_t capture_time_ms,
+                          size_t bytes,
+                          bool retransmission) = 0;
+};
+
+class TransportSequenceNumberAllocator {
+ public:
+  TransportSequenceNumberAllocator() {}
+  virtual ~TransportSequenceNumberAllocator() {}
+
+  virtual uint16_t AllocateSequenceNumber() = 0;
+};
+
 }  // namespace webrtc
 #endif // WEBRTC_MODULES_RTP_RTCP_INTERFACE_RTP_RTCP_DEFINES_H_