Use TimeTicks instead of gettimeofday in ProcessMetrics.

base/process/process_metrics_win.cc

 // Copyright (c) 2013 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 "base/process/process_metrics.h"
 
 #include <windows.h>
 #include <psapi.h>
 
 #include "base/logging.h"
@@ skipping 177 matching lines @@
 }
 
 static uint64 FileTimeToUTC(const FILETIME& ftime) {
   LARGE_INTEGER li;
   li.LowPart = ftime.dwLowDateTime;
   li.HighPart = ftime.dwHighDateTime;
   return li.QuadPart;
 }
 
 double ProcessMetrics::GetCPUUsage() {
-  FILETIME now;
   FILETIME creation_time;
   FILETIME exit_time;
   FILETIME kernel_time;
   FILETIME user_time;
 
-  GetSystemTimeAsFileTime(&now);
-
   if (!GetProcessTimes(process_, &creation_time, &exit_time,
                        &kernel_time, &user_time)) {
     // We don't assert here because in some cases (such as in the Task Manager)
     // we may call this function on a process that has just exited but we have
     // not yet received the notification.
     return 0;
   }
   int64 system_time = (FileTimeToUTC(kernel_time) + FileTimeToUTC(user_time)) /
                         processor_count_;
-  int64 time = FileTimeToUTC(now);
+  TimeTicks time = TimeTicks::Now();
 
-  if ((last_system_time_ == 0) || (last_cpu_time_ == 0)) {
+  if (last_system_time_ == 0) {
     // First call, just set the last values.
     last_system_time_ = system_time;
     last_cpu_time_ = time;
     return 0;
   }
 
   int64 system_time_delta = system_time - last_system_time_;
-  int64 time_delta = time - last_cpu_time_;
+  // FILETIME is in 100-nanosecond units, so this needs microseconds times 10.
+  int64 time_delta = (time - last_cpu_time_).InMicroseconds() * 10;
   DCHECK_NE(0U, time_delta);
   if (time_delta == 0)
     return 0;
 
   // We add time_delta / 2 so the result is rounded.
   int cpu = static_cast<int>((system_time_delta * 100 + time_delta / 2) /
                              time_delta);
 
   last_system_time_ = system_time;
   last_cpu_time_ = time;
@@ skipping 26 matching lines @@
   return true;
 }
 
 bool ProcessMetrics::GetIOCounters(IoCounters* io_counters) const {
   return GetProcessIoCounters(process_, io_counters) != FALSE;
 }
 
 ProcessMetrics::ProcessMetrics(ProcessHandle process)
     : process_(process),
       processor_count_(base::SysInfo::NumberOfProcessors()),
-      last_cpu_time_(0),
       last_system_time_(0) {
 }
 
 // GetPerformanceInfo is not available on WIN2K.  So we'll
 // load it on-the-fly.
 const wchar_t kPsapiDllName[] = L"psapi.dll";
 typedef BOOL (WINAPI *GetPerformanceInfoFunction) (
     PPERFORMANCE_INFORMATION pPerformanceInformation,
     DWORD cb);
 
@@ skipping 23 matching lines @@
 
   PERFORMANCE_INFORMATION info;
   if (!InternalGetPerformanceInfo(&info, sizeof(info))) {
     DLOG(ERROR) << "Failed to fetch internal performance info.";
     return 0;
   }
   return (info.CommitTotal * system_info.dwPageSize) / 1024;
 }
 
 }  // namespace base