Implement video frame acknowledgements in the chromoting protocol.

remoting/protocol/client_video_dispatcher.cc

 // Copyright 2014 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.
 
 #include "remoting/protocol/client_video_dispatcher.h"
 
 #include "base/bind.h"
+#include "base/callback_helpers.h"
 #include "net/socket/stream_socket.h"
 #include "remoting/base/constants.h"
 #include "remoting/proto/video.pb.h"
+#include "remoting/protocol/message_serialization.h"
 #include "remoting/protocol/video_stub.h"
 
 namespace remoting {
 namespace protocol {
 
+struct ClientVideoDispatcher::PendingFrame {
+  PendingFrame(int frame_id)
+      : frame_id(frame_id),
+        done(false) {}
+  int frame_id;
+  bool done;
+};
+
 ClientVideoDispatcher::ClientVideoDispatcher(VideoStub* video_stub)
     : ChannelDispatcherBase(kVideoChannelName),
-      parser_(base::Bind(&VideoStub::ProcessVideoPacket,
-                         base::Unretained(video_stub)),
+      video_stub_(video_stub),
+      parser_(base::Bind(&ClientVideoDispatcher::ProcessVideoPacket,
+                         base::Unretained(this)),
               reader()) {
 }
 
 ClientVideoDispatcher::~ClientVideoDispatcher() {
 }
 
+void ClientVideoDispatcher::ProcessVideoPacket(
+    scoped_ptr<VideoPacket> video_packet,
+    const base::Closure& done) {
+  base::ScopedClosureRunner done_runner(done);
+
+  int frame_id = video_packet->frame_id();
+
+  if (!video_packet->has_frame_id()) {
+    video_stub_->ProcessVideoPacket(video_packet.Pass(), done_runner.Release());
+    return;
+  }
+
+  PendingFramesList::iterator pending_frame =
+      pending_frames_.insert(pending_frames_.end(), PendingFrame(frame_id));
+
+  video_stub_->ProcessVideoPacket(
+      video_packet.Pass(), base::Bind(&ClientVideoDispatcher::OnPacketDone,
+                                      base::Unretained(this), pending_frame));
+
+}
+
+void ClientVideoDispatcher::OnPacketDone(
+    PendingFramesList::iterator pending_frame) {
+  // Mark the frame as done.
+  DCHECK(!pending_frame->done);
+  pending_frame->done = true;
+
+  // Send VideoAck for all packets in the head of the queue that have finished
+  // rendering.
+  while (!pending_frames_.empty() && pending_frames_.front().done) {
+    VideoAck ack_message;
+    ack_message.set_frame_id(pending_frames_.front().frame_id);
+    writer()->Write(SerializeAndFrameMessage(ack_message), base::Closure());
+    pending_frames_.pop_front();
+  }
+}
+
 }  // namespace protocol
 }  // namespace remoting