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

remoting/host/process_stats_sender.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/process_stats_sender.h"
+
+#include <utility>
+
+#include "base/location.h"
+#include "base/logging.h"
+#include "remoting/host/process_stats_agent.h"
+#include "remoting/host/process_stats_util.h"
+
+namespace remoting {
+
+ProcessStatsSender::ProcessStatsSender(
+    protocol::ProcessStatsStub* host_stats_stub,
+    base::TimeDelta interval,
+    std::initializer_list<ProcessStatsAgent*> agents)
+    : host_stats_stub_(host_stats_stub),
+      agents_(agents),
+      thread_checker_() {
+  DCHECK(thread_checker_.CalledOnValidThread());
+  DCHECK(host_stats_stub_);
+  DCHECK(!interval.is_zero());
+  DCHECK(!agents_.empty());
+
+  timer_.Start(FROM_HERE, interval, this, &ProcessStatsSender::ReportUsage);
+}
+
+ProcessStatsSender::~ProcessStatsSender() {
+  DCHECK(thread_checker_.CalledOnValidThread());
+  timer_.Stop();
+}
+
+void ProcessStatsSender::ReportUsage() {
+  DCHECK(thread_checker_.CalledOnValidThread());
+
+  std::vector<protocol::ProcessResourceUsage> usages;
+  for (auto* const agent : agents_) {
+    DCHECK(agent);
+    protocol::ProcessResourceUsage usage = agent->GetResourceUsage();
+    if (!IsEmptyProcessResourceUsage(usage)) {
+      usages.push_back(std::move(usage));
+    }
+  }
+
+  host_stats_stub_->OnProcessStats(AggregateProcessResourceUsage(usages));
+}
+
+}  // namespace remoting