Add client and host dispatchers for video_stats channel to send video stats from host to client.

remoting/protocol/client_video_stats_dispatcher.cc

+// Copyright 2016 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_stats_dispatcher.h"
+
+#include <utility>
+
+#include "base/bind.h"
+#include "base/callback_helpers.h"
+#include "net/socket/stream_socket.h"
+#include "remoting/base/compound_buffer.h"
+#include "remoting/proto/video_stats.pb.h"
+#include "remoting/protocol/frame_stats.h"
+#include "remoting/protocol/message_pipe.h"
+#include "remoting/protocol/message_serialization.h"
+#include "remoting/protocol/video_stats_stub.h"
+
+namespace remoting {
+namespace protocol {
+
+ClientVideoStatsDispatcher::ClientVideoStatsDispatcher(
+    const std::string& stream_name,
+    VideoStatsStub* video_stats_stub)
+    : ChannelDispatcherBase(kVideoStatsChannelNamePrefix + stream_name),

[Jamie, 2016/07/22 17:13:52]

Did you consider passing the stream name in the protobuf rather than the channel
name, and having a single channel for all video stats?

[Sergey Ulanov, 2016/07/22 17:47:47]

Yes. I think it would make code more complex in case there are multiple channels
(as the messages would have to be demultiplexed on the receiver side somewhere)
and all messages would be slightly bigger.
With WebRTC/SCTP data channels are cheap, so there are no issues with having one
video_stats data channel per video stream.

+      video_stats_stub_(video_stats_stub) {}
+
+ClientVideoStatsDispatcher::~ClientVideoStatsDispatcher() {}
+
+void ClientVideoStatsDispatcher::OnIncomingMessage(
+    std::unique_ptr<CompoundBuffer> message) {
+  std::unique_ptr<FrameStatsMessage> stats_proto =
+      ParseMessage<FrameStatsMessage>(message.get());
+  if (!stats_proto)
+    return;
+
+  if (!stats_proto->has_frame_id()) {
+    LOG(ERROR) << "Received invalid FrameStatsMessage.";
+    return;
+  }
+  video_stats_stub_->OnVideoFrameStats(
+      stats_proto->frame_id(),
+      HostFrameStats::FromFrameStatsMessage(*stats_proto));
+}
+
+}  // namespace protocol
+}  // namespace remoting