It's going to be removed from Chromium, see https://crbug.com/812523.

/cc @electron/code-owners 
shell/browser/api/electron_api_app.cc
std::vector<gin_helper::Dictionary> result;
  result.reserve(app_metrics_.size());
  int processor_count = base::SysInfo::NumberOfProcessors();
  for (const auto& process_metric : app_metrics_) {
    gin_helper::Dictionary pid_dict = gin::Dictionary::CreateEmpty(isolate);
    gin_helper::Dictionary cpu_dict = gin::Dictionary::CreateEmpty(isolate);
    
    gin_helper::Dictionary(isolate, pid_dict.GetHandle())
        .SetHidden("simple", true);
    gin_helper::Dictionary(isolate, cpu_dict.GetHandle())
        .SetHidden("simple", true);
    cpu_dict.Set(
        "percentCPUUsage",
        process_metric.second->metrics->GetPlatformIndependentCPUUsage() /
            processor_count);
#if !defined(OS_WIN)
    cpu_dict.Set("idleWakeupsPerSecond",
                 process_metric.second->metrics->GetIdleWakeupsPerSecond());
#else
    
    
    
    cpu_dict.Set("idleWakeupsPerSecond", 0);
#endif
    pid_dict.Set("cpu", cpu_dict);
    pid_dict.Set("pid", process_metric.second->process.Pid());
    pid_dict.Set("type", content::GetProcessTypeNameInEnglish(
                             process_metric.second->type));
    pid_dict.Set("creationTime",
                 process_metric.second->process.CreationTime().ToJsTime());