Revert of Delete unused code from systeminfo.

webrtc/system_wrappers/source/cpu_info.cc

 /*
  *  Copyright (c) 2011 The WebRTC project authors. All Rights Reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
 #include "webrtc/system_wrappers/include/cpu_info.h"
 
-#if defined(WEBRTC_WIN)
-#include <winsock2.h>
-#include <windows.h>
-#ifndef EXCLUDE_D3D9
-#include <d3d9.h>
-#endif
-#elif defined(WEBRTC_LINUX)
-#include <unistd.h>
-#endif
-#if defined(WEBRTC_MAC)
-#include <sys/sysctl.h>
-#endif
-
-#include "webrtc/base/logging.h"
-
-namespace internal {
-static int DetectNumberOfCores() {
-  // We fall back on assuming a single core in case of errors.
-  int number_of_cores = 1;
-
-#if defined(WEBRTC_WIN)
-  SYSTEM_INFO si;
-  GetSystemInfo(&si);
-  number_of_cores = static_cast<int>(si.dwNumberOfProcessors);
-#elif defined(WEBRTC_LINUX) || defined(WEBRTC_ANDROID)
-  number_of_cores = static_cast<int>(sysconf(_SC_NPROCESSORS_ONLN));
-#elif defined(WEBRTC_MAC)
-  int name[] = {CTL_HW, HW_AVAILCPU};
-  size_t size = sizeof(number_of_cores);
-  if (0 != sysctl(name, 2, &number_of_cores, &size, NULL, 0)) {
-    LOG(LS_ERROR) << "Failed to get number of cores";
-    number_of_cores = 1;
-  }
-#else
-  LOG(LS_ERROR) << "No function to get number of cores";
-#endif
-
-  LOG(LS_INFO) << "Available number of cores: " << number_of_cores;
-
-  return number_of_cores;
-}
-}
+#include "webrtc/base/systeminfo.h"
 
 namespace webrtc {
 
 uint32_t CpuInfo::DetectNumberOfCores() {
-  // Statically cache the number of system cores available since if the process
-  // is running in a sandbox, we may only be able to read the value once (before
-  // the sandbox is initialized) and not thereafter.
-  // For more information see crbug.com/176522.
-  static uint32_t logical_cpus = 0;
-  if (!logical_cpus)
-    logical_cpus = static_cast<uint32_t>(internal::DetectNumberOfCores());
-  return logical_cpus;
+  return static_cast<uint32_t>(rtc::SystemInfo::GetMaxCpus());
 }
 
 }  // namespace webrtc