Cast: First stab at implementing adaptive latency

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 89e654d81baa7c631e8d04e5e21cbf0d219d3710..d244cbdadc872e555b25c359f08c238f2726e822 100644
--- a/media/cast/sender/frame_sender.h
+++ b/media/cast/sender/frame_sender.h
@@ -29,7 +29,8 @@ class FrameSender {
               int rtp_timebase,
               uint32 ssrc,
               double max_frame_rate,
-              base::TimeDelta playout_delay,
+              base::TimeDelta min_playout_delay,
+              base::TimeDelta max_playout_delay,
               CongestionControl* congestion_control);
   virtual ~FrameSender();
 
@@ -58,6 +59,7 @@ class FrameSender {
   void SendRtcpReport(bool schedule_future_reports);
 
   void OnMeasuredRoundTripTime(base::TimeDelta rtt);
+  base::TimeDelta AverageRTT();
 
   const scoped_refptr<CastEnvironment> cast_environment_;
 
@@ -108,6 +110,8 @@ class FrameSender {
   // environment (sender/receiver hardware performance, network conditions,
   // etc.).
   base::TimeDelta target_playout_delay_;
+  base::TimeDelta min_playout_delay_;
+  base::TimeDelta max_playout_delay_;
 
   // If true, we transmit the target playout delay to the receiver.
   bool send_target_playout_delay_;
@@ -167,6 +171,10 @@ class FrameSender {
   // The most recently measured round trip time.
   base::TimeDelta current_round_trip_time_;
 
+  // Used to keep track of historic round-trip times.
+  std::deque<base::TimeDelta> recent_round_trip_times_;
+  base::TimeDelta recent_round_trip_times_sum_;
+
   // NOTE: Weak pointers must be invalidated before all other member variables.
   base::WeakPtrFactory<FrameSender> weak_factory_;