Implement video frame acknowledgements in the chromoting protocol.

remoting/host/capture_scheduler.h

Index: remoting/host/capture_scheduler.h
diff --git a/remoting/host/capture_scheduler.h b/remoting/host/capture_scheduler.h
index 610b35ba490b9cb1ef4b5bcedbde46bd6d28c624..29c2c5703d47b0a9c35a5bfc47375078f39087c0 100644
--- a/remoting/host/capture_scheduler.h
+++ b/remoting/host/capture_scheduler.h
@@ -22,7 +22,7 @@ namespace remoting {
 // taking into account capture delay, encoder delay, network bandwidth, etc.
 class CaptureScheduler : public base::NonThreadSafe {
  public:
-  explicit CaptureScheduler(const base::Closure& capture_closure);
+  CaptureScheduler(const base::Closure& capture_closure, bool acks_supported);
   ~CaptureScheduler();
 
   // Starts the scheduler.
@@ -40,6 +40,16 @@ class CaptureScheduler : public base::NonThreadSafe {
   // Notifies the scheduler than a frame has been sent.
   void OnFrameSent();
 
+  // Notifies the scheduler than a frame has been acknowledged.
+  void OnFrameAck();
+
+  // Sets maximum number of pending frames in the sending queue. When ACKs are
+  // supported frames is considered to be pending until ACK message is received,

[Wez, 2015/02/03 00:54:32]

s/is/are

[Sergey Ulanov, 2015/02/09 19:14:54]

Removed this function now

+  // otherwise it's pending until it's sent (OnFrameSent() is called).

[Wez, 2015/02/03 00:54:32]

If the two things are treated equivalently, simply dependent on whether ACKs are
supported, then why not deal with the difference in the lower levels and avoid
polluting the CaptureScheduler with both concepts?

[Sergey Ulanov, 2015/02/09 19:14:54]

Removed this function now

+  void set_maximum_pending_frames(int max_pending_frames) {
+    max_pending_frames_ = max_pending_frames;
+  }
+
   // Sets minimum interval between frames.
   void set_minimum_interval(base::TimeDelta minimum_interval) {
     minimum_interval_ = minimum_interval;
@@ -68,6 +78,12 @@ class CaptureScheduler : public base::NonThreadSafe {
 
   base::Closure capture_closure_;
 
+  // Set to true if the connection supports video frame acknowledgments.
+  bool acks_supported_;
+
+  // Maximum number of pending frames.
+  int max_pending_frames_;
+
   scoped_ptr<base::TickClock> tick_clock_;
 
   // Timer used to schedule CaptureNextFrame().
@@ -81,7 +97,9 @@ class CaptureScheduler : public base::NonThreadSafe {
   RunningAverage capture_time_;
   RunningAverage encode_time_;
 
-  int pending_frames_;
+  int num_encoding_frames_;
+  int num_sending_frames_;
+
   bool capture_pending_;
   base::TimeTicks last_capture_started_time_;
   bool is_paused_;