More reliable keep-alive video packets.

remoting/host/video_scheduler.h

Index: remoting/host/video_scheduler.h
diff --git a/remoting/host/video_scheduler.h b/remoting/host/video_scheduler.h
index f2eabd9744bbbcc94b178944ab0f4d48e1c55286..94fc7951dbc4e50df29f42518709d848d7eb2c01 100644
--- a/remoting/host/video_scheduler.h
+++ b/remoting/host/video_scheduler.h
@@ -140,7 +140,13 @@ class VideoScheduler : public base::RefCountedThreadSafe<VideoScheduler>,
 
   // 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);
@@ -173,6 +179,10 @@ class VideoScheduler : public base::RefCountedThreadSafe<VideoScheduler>,
   // 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.