[Chromoting] Retrieve process resource usage (ProcessStats) and its tests

remoting/host/forward_process_stats_agent.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/host/forward_process_stats_agent.h"
+
+namespace remoting {
+namespace host {
+
+ForwardProcessStatsAgent::ForwardProcessStatsAgent() = default;
+ForwardProcessStatsAgent::~ForwardProcessStatsAgent() = default;
+
+protocol::ProcessResourceUsage ForwardProcessStatsAgent::GetResourceUsage() {
+  base::AutoLock lock(lock_);
+  return usage_;
+}
+
+void ForwardProcessStatsAgent::OnProcessStats(
+    const protocol::ProcessResourceUsage& usage) {
+  base::AutoLock lock(lock_);
+  usage_ = usage;
+}
+
+}  // namespace host
+}  // namespace remoting