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

remoting/base/process_stats.h

+// 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_BASE_PROCESS_STATS_H_
+#define REMOTING_BASE_PROCESS_STATS_H_
+
+#include <memory>
+#include <vector>
+
+#include "base/time/time.h"
+#include "base/timer/timer.h"
+#include "remoting/base/process_stats_agent.h"
+#include "remoting/base/process_stats_stub.h"
+#include "remoting/proto/process_stats.pb.h"

[Sergey Ulanov, 2017/04/03 23:50:21]

base shouldn't depend on proto.

[Hzj_jie, 2017/04/05 20:52:16]

These files have been moved to host.

+
+namespace remoting {
+
+// A component to report process statistic data regularly.
+class ProcessStats final {

[Sergey Ulanov, 2017/04/03 23:50:21]

Maybe ProcessStatsSender?

[Hzj_jie, 2017/04/05 20:52:16]

Done.

+ public:
+  // ProcessStats does not take the ownership of |host_stats_stub|. It needs to
+  // be outlived this instance.

[Sergey Ulanov, 2017/04/03 23:50:21]

s/It needs to be outlived this instance./It must outlive the ProcessStats
object./

[Hzj_jie, 2017/04/05 20:52:16]

Done.

+  ProcessStats(ProcessStatsStub* host_stats_stub, base::TimeDelta interval);
+
+  // Needs to be destructed on the same thread as constructing.
+  ~ProcessStats();
+
+  void AddProcessStatsAgent(std::unique_ptr<ProcessStatsAgent> agent);
+
+  // ProcessStats starts immediately, and reports the statistic data to
+  // |host_stats_stub| once per |interval_|.
+  void Start();
+
+  void Stop();

[Sergey Ulanov, 2017/04/03 23:50:21]

Do we need this methods? Would it be better just destroy this object?

[Hzj_jie, 2017/04/05 20:52:16]

Emmm, indeed I believe this class should start immediately after its
constructor, and stop in destruction. But consumers may need to add agents to it
before it can actually work. I would argue if no agent is added, this class does
nothing anyway. I think we can remove both Start() and Stop() functions, but add
a ThreadChecker in AddProcessStatsAgent() function to ensure no cross-threads
violence.

+
+ private:
+  void ReportUsage();
+
+  ProcessStatsStub* const host_stats_stub_;
+  const base::TimeDelta interval_;
+  std::vector<std::unique_ptr<ProcessStatsAgent>> agents_;
+  base::RepeatingTimer timer_;
+};
+
+}  // namespace remoting
+
+#endif  // REMOTING_BASE_PROCESS_STATS_H_