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

remoting/host/forward_process_stats_agent.h

Index: remoting/host/forward_process_stats_agent.h
diff --git a/remoting/host/forward_process_stats_agent.h b/remoting/host/forward_process_stats_agent.h
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+// 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.
+
+#ifndef REMOTING_HOST_FORWARD_PROCESS_STATS_AGENT_H_
+#define REMOTING_HOST_FORWARD_PROCESS_STATS_AGENT_H_
+
+#include "base/threading/thread_checker.h"
+#include "remoting/host/process_stats_agent.h"
+#include "remoting/proto/process_stats.pb.h"
+
+namespace remoting {
+
+// ProcessStatsAgent implementation that returns stats passed to
+// OnProcessStats(). Used to collect stats from processes other than the current
+// one. All public functions, not including constructor and destructor, of the
+// object of ForwardProcessStatsAgent are expected to be called in a same
+// thread.
+class ForwardProcessStatsAgent final : public ProcessStatsAgent {
+ public:
+  ForwardProcessStatsAgent();
+  ~ForwardProcessStatsAgent() override;
+
+  void OnProcessStats(const protocol::ProcessResourceUsage& usage);
+
+  // ProcessStatsAgent implementation.
+  protocol::ProcessResourceUsage GetResourceUsage() override;
+
+ private:
+  base::ThreadChecker thread_checker_;
+  protocol::ProcessResourceUsage usage_;
+};
+
+}  // namespace remoting
+
+#endif  // REMOTING_HOST_FORWARD_PROCESS_STATS_AGENT_H_