[Chromoting] Add ProcessStatsDispatcher to send process stats to the client

remoting/protocol/process_stats_adapter.cc

+// Copyright 2017 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/process_stats_adapter.h"
+
+#include <utility>
+
+#include "base/logging.h"
+#include "remoting/base/constants.h"
+#include "remoting/proto/control.pb.h"
+#include "remoting/proto/process_stats.pb.h"
+#include "remoting/protocol/client_stub.h"
+
+namespace remoting {
+namespace protocol {
+
+ProcessStatsAdapter::ProcessStatsAdapter(ClientStub* client_stub)
+    : client_stub_(client_stub) {
+  DCHECK(client_stub_);
+}
+ProcessStatsAdapter::~ProcessStatsAdapter() = default;
+
+void ProcessStatsAdapter::OnProcessStats(
+    const AggregatedProcessResourceUsage& usage) {
+  protocol::ExtensionMessage message;
+  message.set_type(extension_message::kProcessStatsType);
+  std::string data;
+  CHECK(usage.SerializeToString(&data));

[joedow, 2017/05/26 16:14:10]

Should this break a release build?  I think a DCHECK is fine, but if we released
a host where there was a problem sending stats data, I don't think I would want
the host to be unusable.

[Sergey Ulanov, 2017/05/26 19:27:30]

All extension messages are serialized using JSON. Using protobuf here would make
it inconsistent.

[Hzj_jie, 2017/05/26 20:42:16]

Reasonable. Though I think there is zero reason this function call would fail.
(The only possible failure here is a 2G+ message
https://cs.chromium.org/chromium/src/third_party/protobuf/src/google/protobuf...)

+  message.set_data(std::move(data));
+
+  client_stub_->DeliverHostMessage(message);

[Sergey Ulanov, 2017/05/26 19:27:30]

If we are using protocol extensions to send these messages then it should be
implemented using HostExtension & HostExtensionSession interfaces.

+}
+
+}  // namespace protocol
+}  // namespace remoting