Refactor: simplify interface of SenderRtcpSession and CastTransport.

media/cast/net/rtcp/sender_rtcp_session.h

Index: media/cast/net/rtcp/sender_rtcp_session.h
diff --git a/media/cast/net/rtcp/sender_rtcp_session.h b/media/cast/net/rtcp/sender_rtcp_session.h
index d32a1ade86fd60014332933e4730954b97909176..2d4cdae05c577abca91e66b9643c11fb190628ff 100644
--- a/media/cast/net/rtcp/sender_rtcp_session.h
+++ b/media/cast/net/rtcp/sender_rtcp_session.h
@@ -28,22 +28,37 @@ typedef std::queue<RtcpSendTimePair> RtcpSendTimeQueue;
 // receiver to maintain clock offsets and synchronize between audio and video.
 //
 // RTCP session on sender handles the following incoming RTCP reports
-// from receiver:
+// from receiver and passes the information to the Client:
 // - Receiver reference time report: Helps with tracking largest timestamp
 //   seen and as a result rejecting old RTCP reports.
-// - Receiver logs: The sender receives log events from the receiver and
-//   invokes a callback passed.
-// - cast message: Receives feedback from receiver on missing packets/frames
-//   and last frame id received and invokes a callback passed.
+// - Receiver logs: The sender receives log events from the receiver.
+// - cast message: Receives feedback from receiver on missing packets/frames,
+//   later frames received, and last frame id.
 // - Last report: The receiver provides feedback on delay since last report
-//   received which helps it compute round trip time and invoke a callback.
+//   received which helps it compute round trip time.
+// - PLI: Receiver sends PLI when decoding error exists on ultra-low latency
+//   applications.
 class SenderRtcpSession : public RtcpSession {
  public:
-  // TODO(xjz): Simplify the interface. http://crbug.com/588275.
-  SenderRtcpSession(const RtcpCastMessageCallback& cast_callback,
-                    const RtcpRttCallback& rtt_callback,
-                    const RtcpLogMessageCallback& log_callback,
-                    const RtcpPliCallback pli_callback,
+  // Interface to handel receiving RTCP messages from RTP receiver.
+  class Client {

[miu, 2016/04/15 23:14:39]

This is identical to RtpSenderRtcpClient, except it adds one more method.  So,
consider just having one interface w/ all 4 methods.  Then, the name of the
interface can just be "RtcpClient" or maybe "RtcpObserver" would be more
descriptive?

[xjz, 2016/04/20 01:09:03]

Done. Named the interface "SenderRtcpObserver".

+   public:
+    virtual ~Client() {}
+
+    // Called to pass the cast message to the Client.
+    virtual void OnCastMessageReceived(const RtcpCastMessage& cast_message) = 0;
+
+    // Called to pass the current Rtt to the Client.
+    virtual void OnRttReceived(base::TimeDelta round_trip_time) = 0;
+
+    // Called to pass the RTP receiver logs to the Client.
+    virtual void OnReceiverLogReceived(const RtcpReceiverLogMessage& log) = 0;
+
+    // Received PLI from RTP receiver.
+    virtual void OnPliReceived() = 0;
+  };
+
+  SenderRtcpSession(std::unique_ptr<Client> client,
                     base::TickClock* clock,            // Not owned.
                     PacedPacketSender* packet_sender,  // Not owned.
                     uint32_t local_ssrc,
@@ -98,11 +113,7 @@ class SenderRtcpSession : public RtcpSession {
   PacedPacketSender* packet_sender_;  // Not owned.
   const uint32_t local_ssrc_;
   const uint32_t remote_ssrc_;
-
-  const RtcpCastMessageCallback cast_callback_;
-  const RtcpRttCallback rtt_callback_;
-  const RtcpLogMessageCallback log_callback_;
-  const RtcpPliCallback pli_callback_;
+  const std::unique_ptr<Client> sender_rtcp_client_;
 
   // Computed from RTCP RRTR report.
   base::TimeTicks largest_seen_timestamp_;