More reliable keep-alive video packets.

remoting/host/video_scheduler.h

 // Copyright (c) 2012 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.
 
 #ifndef REMOTING_HOST_VIDEO_SCHEDULER_H_
 #define REMOTING_HOST_VIDEO_SCHEDULER_H_
 
 #include <vector>
 
 #include "base/basictypes.h"
@@ skipping 122 matching lines @@
   // Called when a frame capture has been encoded & sent to the client.
   void FrameCaptureCompleted();
 
   // Network thread -----------------------------------------------------------
 
   // Send |packet| to the client, unless we are in the process of stopping.
   void SendVideoPacket(scoped_ptr<VideoPacket> packet);
 
   // Callback passed to |video_stub_| for the last packet in each frame, to
   // rate-limit frame captures to network throughput.
-  void VideoFrameSentCallback();
+  void OnVideoPacketSent();
+
+  // Called by |keep_alive_timer_|.
+  void SendKeepAlivePacket();
+
+  // Callback for |video_stub_| called after a keep-alive packet is sent.
+  void OnKeepAlivePacketSent();
 
   // Send updated cursor shape to client.
   void SendCursorShape(scoped_ptr<protocol::CursorShapeInfo> cursor_shape);
 
   // Encoder thread -----------------------------------------------------------
 
   // Encode a frame, passing generated VideoPackets to SendVideoPacket().
   void EncodeFrame(scoped_ptr<webrtc::DesktopFrame> frame,
                    int64 sequence_number);
 
@@ skipping 12 matching lines @@
   scoped_ptr<VideoEncoder> encoder_;
 
   // Interfaces through which video frames and cursor shapes are passed to the
   // client. These members are always accessed on the network thread.
   protocol::CursorShapeStub* cursor_stub_;
   protocol::VideoStub* video_stub_;
 
   // Timer used to schedule CaptureNextFrame().
   scoped_ptr<base::OneShotTimer<VideoScheduler> > capture_timer_;
 
+  // Timer used to ensure that we send empty keep-alive frames to the client
+  // even when the video stream is paused or encoder is busy.
+  scoped_ptr<base::DelayTimer<VideoScheduler> > keep_alive_timer_;
+
   // The number of frames being processed, i.e. frames that we are currently
   // capturing, encoding or sending. The value is capped at 2 to minimize
   // latency.
   int pending_frames_;
 
   // Set when the capturer is capturing a frame.
   bool capture_pending_;
 
   // True if the previous scheduled capture was skipped.
   bool did_skip_frame_;
 
   // True if capture of video frames is paused.
   bool is_paused_;
 
   // This is a number updated by client to trace performance.
   int64 sequence_number_;
 
   // An object to schedule capturing.
   CaptureScheduler scheduler_;
 
   DISALLOW_COPY_AND_ASSIGN(VideoScheduler);
 };
 
 }  // namespace remoting
 
 #endif  // REMOTING_HOST_VIDEO_SCHEDULER_H_