Implement video frame acknowledgements in the chromoting protocol.

remoting/protocol/host_video_dispatcher.h

Index: remoting/protocol/host_video_dispatcher.h
diff --git a/remoting/protocol/host_video_dispatcher.h b/remoting/protocol/host_video_dispatcher.h
index c1a957397c0ab6a018f12b8414df98a84b55bc9d..0c17e2d2403ceb49212335961840f57128204de9 100644
--- a/remoting/protocol/host_video_dispatcher.h
+++ b/remoting/protocol/host_video_dispatcher.h
@@ -5,17 +5,19 @@
 #ifndef REMOTING_PROTOCOL_HOST_VIDEO_DISPATCHER_H_
 #define REMOTING_PROTOCOL_HOST_VIDEO_DISPATCHER_H_
 
+#include <deque>
 #include <string>
 
 #include "base/compiler_specific.h"
-#include "remoting/protocol/buffered_socket_writer.h"
+#include "remoting/proto/video.pb.h"
 #include "remoting/protocol/channel_dispatcher_base.h"
-#include "remoting/protocol/video_stub.h"
+#include "remoting/protocol/protobuf_message_parser.h"
+#include "remoting/protocol/video_sender.h"
 
 namespace remoting {
 namespace protocol {
 
-class HostVideoDispatcher : public ChannelDispatcherBase, public VideoStub {
+class HostVideoDispatcher : public ChannelDispatcherBase, public VideoSender {
  public:
   HostVideoDispatcher();
   ~HostVideoDispatcher() override;
@@ -23,8 +25,23 @@ class HostVideoDispatcher : public ChannelDispatcherBase, public VideoStub {
   // VideoStub interface.
   void ProcessVideoPacket(scoped_ptr<VideoPacket> packet,
                           const base::Closure& done) override;
+  bool SupportsAcks() override;
 
  private:
+  struct PendingFrame {
+    PendingFrame(int frame_id, const base::Closure& done);
+
+    int32_t frame_id;
+    base::Closure done;
+  };
+
+  void OnVideoAck(scoped_ptr<VideoAck> ack, const base::Closure& done);
+
+  int32_t frame_id_;
+  ProtobufMessageParser<VideoAck> parser_;
+
+  std::deque<PendingFrame> pending_frames_;
+
   DISALLOW_COPY_AND_ASSIGN(HostVideoDispatcher);
 };