Refactor: simplify interface of SenderRtcpSession and CastTransport.

media/cast/sender/frame_sender.h

Index: media/cast/sender/frame_sender.h
diff --git a/media/cast/sender/frame_sender.h b/media/cast/sender/frame_sender.h
index 7a58abaa9e387e3b2020a535d8330d05c7b741c6..11dded3d55ab48cca4104e58447a8c816fe78d53 100644
--- a/media/cast/sender/frame_sender.h
+++ b/media/cast/sender/frame_sender.h
@@ -53,6 +53,14 @@ class FrameSender {
   void SendEncodedFrame(int requested_bitrate_before_encode,
                         scoped_ptr<SenderEncodedFrame> encoded_frame);
 
+  // Protected for testability.
+  void OnReceivedCastFeedback(const RtcpCastMessage& cast_feedback);

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

Instead of making these methods public, consider one of two options:

1. Have FrameSender extend and implement the RtpSenderRtcpClient interface
directly (i.e., no separate class).

-or-

2. You should give the RtpSenderRtcpClient subclass access to the protected
members of FrameSender.  This can be done by forward-declaring
FrameSenderRtcpClient as an inner class of FrameSender.  Meaning:

  class FrameSender {
    ...
   protected:
    class RtcpClient;
    ...
  };

Then, in frame_sender.cc:

class FrameSender::RtcpClient : public RtpSenderRtcpClient {
  ...code in this class has access to protected and private members of
FrameSender...
};

(And, note that you only need one of these; and not a separate one for
AudioSender vs VideoSender.)

IMO, #1 would be much simpler than #2.  Perhaps the same approach would work for
other classes involved in this change?

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

Done. Choose #2 for convenience.

+
+  // Called when a Pli message is received.
+  void OnReceivedPli();
+
+  void OnMeasuredRoundTripTime(base::TimeDelta rtt);
+
  protected:
   // Returns the number of frames in the encoder's backlog.
   virtual int GetNumberOfFramesInEncoder() const = 0;
@@ -66,8 +74,6 @@ class FrameSender {
   void ScheduleNextRtcpReport();
   void SendRtcpReport(bool schedule_future_reports);
 
-  void OnMeasuredRoundTripTime(base::TimeDelta rtt);
-
   const scoped_refptr<CastEnvironment> cast_environment_;
 
   // Sends encoded frames over the configured transport (e.g., UDP).  In
@@ -89,12 +95,6 @@ class FrameSender {
   void ResendCheck();
   void ResendForKickstart();
 
-  // Protected for testability.
-  void OnReceivedCastFeedback(const RtcpCastMessage& cast_feedback);
-
-  // Called when a Pli message is received.
-  void OnReceivedPli();
-
   // Returns true if too many frames would be in-flight by encoding and sending
   // the next frame having the given |frame_duration|.
   bool ShouldDropNextFrame(base::TimeDelta frame_duration) const;