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

remoting/host/process_stats_agent.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_HOST_PROCESS_STATS_AGENT_H_
-#define REMOTING_HOST_PROCESS_STATS_AGENT_H_
-
-#include "remoting/proto/process_stats.pb.h"
-
-namespace remoting {
-
-// An interface to report the process statistic data.
-class ProcessStatsAgent {
- public:
-  ProcessStatsAgent() = default;
-  virtual ~ProcessStatsAgent() = default;
-
-  // This function is expected to be executed in an IO-disallowed thread: if the
-  // implementation requires IO access or may cost a significant amount of time,
-  // using a background thread is preferred.
-  virtual protocol::ProcessResourceUsage GetResourceUsage() = 0;
-};
-
-}  // namespace remoting
-
-#endif  // REMOTING_HOST_PROCESS_STATS_AGENT_H_