[Cast] Remove AudioDecoder's dependency on WebRTC, and refactor/clean-up AudioReceiver.

media/cast/rtp_receiver/rtp_receiver.h

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // Interface to the rtp receiver.
 
 #ifndef MEDIA_CAST_RTP_RECEIVER_RTP_RECEIVER_H_
 #define MEDIA_CAST_RTP_RECEIVER_RTP_RECEIVER_H_
 
 #include "base/memory/scoped_ptr.h"
 #include "media/cast/cast_config.h"
 #include "media/cast/rtcp/rtcp.h"
 #include "media/cast/rtp_receiver/rtp_receiver_defines.h"
 
 namespace media {
 namespace cast {
 
 class RtpData {
  public:
   virtual void OnReceivedPayloadData(const uint8* payload_data,
                                      size_t payload_size,
-                                     const RtpCastHeader* rtp_header) = 0;
+                                     const RtpCastHeader& rtp_header) = 0;
 
  protected:
   virtual ~RtpData() {}
 };
 
 class ReceiverStats;
 class RtpParser;
 
-class RtpReceiver {
+class RtpReceiver : public RtpReceiverStatistics {
  public:
   RtpReceiver(base::TickClock* clock,
               const AudioReceiverConfig* audio_config,
               const VideoReceiverConfig* video_config,
               RtpData* incoming_payload_callback);
-  ~RtpReceiver();
+  virtual ~RtpReceiver();
 
   static uint32 GetSsrcOfSender(const uint8* rtcp_buffer, size_t length);
 
   bool ReceivedPacket(const uint8* packet, size_t length);
 
-  void GetStatistics(uint8* fraction_lost,
-                     uint32* cumulative_lost,  // 24 bits valid.
-                     uint32* extended_high_sequence_number,
-                     uint32* jitter);
+  virtual void GetStatistics(uint8* fraction_lost,
+                             uint32* cumulative_lost,  // 24 bits valid.
+                             uint32* extended_high_sequence_number,
+                             uint32* jitter) OVERRIDE;
 
  private:
   scoped_ptr<ReceiverStats> stats_;
   scoped_ptr<RtpParser> parser_;
 
   DISALLOW_COPY_AND_ASSIGN(RtpReceiver);
 };
 
 }  // namespace cast
 }  // namespace media
 
 #endif  // MEDIA_CAST_RTP_RECEIVER_RTP_RECEIVER_H_